diff --git a/app/build.gradle b/app/build.gradle
index 7ca23dc..49eeccf 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -26,5 +26,5 @@ dependencies {
     compile 'com.android.support:appcompat-v7:24.2.1'
     compile 'com.android.support:design:24.2.1'
     compile 'org.osmdroid:osmdroid-android:5.2@aar'
-    compile 'com.google.code.gson:gson:2.4'
+    compile 'com.google.code.gson:gson:2.7'
 }
diff --git a/app/src/main/java/org/y20k/trackbook/MainActivity.java b/app/src/main/java/org/y20k/trackbook/MainActivity.java
index f9bac8f..c276ca3 100644
--- a/app/src/main/java/org/y20k/trackbook/MainActivity.java
+++ b/app/src/main/java/org/y20k/trackbook/MainActivity.java
@@ -361,11 +361,19 @@ public class MainActivity extends AppCompatActivity implements TrackbookKeys {
             // get last location from MainActivity Fragment
             Location lastLocation = mMainActivityMapFragment.getCurrentBestLocation();
 
-            // start tracker service
-            Intent intent = new Intent(this, TrackerService.class);
-            intent.setAction(ACTION_START);
-            intent.putExtra(EXTRA_LAST_LOCATION, lastLocation);
-            startService(intent);
+            if (lastLocation != null) {
+                // start tracker service
+                Intent intent = new Intent(this, TrackerService.class);
+                intent.setAction(ACTION_START);
+                intent.putExtra(EXTRA_LAST_LOCATION, lastLocation);
+                startService(intent);
+            } else {
+                Toast.makeText(this, getString(R.string.toast_message_location_services_not_ready), Toast.LENGTH_LONG).show();
+                // change state back
+                mTrackerServiceRunning = false;
+                setFloatingActionButtonState();
+            }
+
         }
 
         // update tracking state in MainActivityMapFragment
diff --git a/app/src/main/java/org/y20k/trackbook/MainActivityMapFragment.java b/app/src/main/java/org/y20k/trackbook/MainActivityMapFragment.java
index f9f5394..4862c36 100644
--- a/app/src/main/java/org/y20k/trackbook/MainActivityMapFragment.java
+++ b/app/src/main/java/org/y20k/trackbook/MainActivityMapFragment.java
@@ -299,25 +299,35 @@ public class MainActivityMapFragment extends Fragment implements TrackbookKeys {
                     // app does not have any location fix
                     mCurrentBestLocation = LocationHelper.determineLastKnownLocation(mLocationManager);
                 }
-                position = convertToGeoPoint(mCurrentBestLocation);
 
-                // center map on current position
-                mController.setCenter(position);
 
-                // mark user's new location on map and remove last marker
-                updateMyLocationMarker();
+                // check if really got a position
+                if (mCurrentBestLocation != null) {
+                    position = convertToGeoPoint(mCurrentBestLocation);
 
-                // inform user about location quality
-                String locationInfo;
-                long locationAge =  (SystemClock.elapsedRealtimeNanos() - mCurrentBestLocation.getElapsedRealtimeNanos()) / 1000000;
-                String locationAgeString = LocationHelper.convertToReadableTime(locationAge, false);
-                if (locationAgeString == null) {
-                    locationAgeString = mActivity.getString(R.string.toast_message_last_location_age_one_hour);
+                    // center map on current position
+                    mController.setCenter(position);
+
+                    // mark user's new location on map and remove last marker
+                    updateMyLocationMarker();
+
+                    // inform user about location quality
+                    String locationInfo;
+                    long locationAge =  (SystemClock.elapsedRealtimeNanos() - mCurrentBestLocation.getElapsedRealtimeNanos()) / 1000000;
+                    String locationAgeString = LocationHelper.convertToReadableTime(locationAge, false);
+                    if (locationAgeString == null) {
+                        locationAgeString = mActivity.getString(R.string.toast_message_last_location_age_one_hour);
+                    }
+                    locationInfo = " " + locationAgeString + " | " + mCurrentBestLocation.getProvider();
+                    Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_last_location) + locationInfo, Toast.LENGTH_LONG).show();
+                    return true;
+                } else {
+                    Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_location_services_not_ready), Toast.LENGTH_LONG).show();
+                    return false;
                 }
-                locationInfo = " " + locationAgeString + " | " + mCurrentBestLocation.getProvider();
-                Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_last_location) + locationInfo, Toast.LENGTH_LONG).show();
 
-                return true;
+
+
 
             // CASE DEFAULT
             default:
@@ -374,6 +384,7 @@ public class MainActivityMapFragment extends Fragment implements TrackbookKeys {
 
     /* Removes track crumbs from map */
     public void clearMap() {
+// TODO clear map or clear intent
         if (mTrackOverlay != null) {
             Toast.makeText(mActivity, mActivity.getString(R.string.toast_message_clear_map), Toast.LENGTH_LONG).show();
             mMapView.getOverlays().remove(mTrackOverlay);
diff --git a/app/src/main/res/values-de/strings.xml b/app/src/main/res/values-de/strings.xml
index 4af7e0c..4ff8f9c 100644
--- a/app/src/main/res/values-de/strings.xml
+++ b/app/src/main/res/values-de/strings.xml
@@ -16,8 +16,8 @@
     <string name="tab_last_track">LETZTE AUFZEICHNUNG</string>
 
     <!-- notification -->
-    <string name="notification_title_trackbook_not_running">Trackbook ist aktiv</string>
-    <string name="notification_title_trackbook_running">Trackbook ist inaktiv</string>
+    <string name="notification_title_trackbook_not_running">Trackbook ist inaktiv</string>
+    <string name="notification_title_trackbook_running">Trackbook ist aktiv</string>
     <string name="notification_stop">Stopp</string>
     <string name="notification_swipe_to_clear_map">(Ausblenden setzt Kartenansicht zurück)</string>
     <string name="notification_content_duration">Dauer</string>
@@ -34,6 +34,7 @@
     <string name="toast_message_no_external_storage">Zugriff auf den externen Speicher verweigert.</string>
     <string name="toast_message_location_offline">Standortdienste sind deaktiviert. Trackbook kann nicht aufzeichnen.</string>
     <string name="toast_message_acquiring_location">Suche aktuellen Standort.</string>
+    <string name="toast_message_location_services_not_ready">Standortdienste noch nicht bereit. Bitte erneut versuchen.</string>
     <string name="toast_message_last_location">Letzte Position:</string>
     <string name="toast_message_clear_map">Kartenansicht wird zurückgesetzt</string>
     <string name="toast_message_last_location_age_one_hour">über eine Stunde</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 04cc638..161c547 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -34,6 +34,7 @@
     <string name="toast_message_no_external_storage">Unable to access external storage.</string>
     <string name="toast_message_location_offline">Location is turned off. Trackbook will not work.</string>
     <string name="toast_message_acquiring_location">Acquiring current location.</string>
+    <string name="toast_message_location_services_not_ready">Location services not ready. Please retry.</string>
     <string name="toast_message_last_location">Last location:</string>
     <string name="toast_message_clear_map">Clearing map.</string>
     <string name="toast_message_last_location_age_one_hour">over one hour</string>