Android Question Location tracker error?

Just saw this error for the first time - can anyone help?

** Service (locationtracker) Create **
locationtracker_service_create (B4A line: 13)
LocationClient1.Initialize("LocationClient1")
java.lang.NoClassDefFoundError: uk.co.martinpearman.b4a.android.gms.location.subclasses.LocationClient
at uk.co.martinpearman.b4a.android.gms.location.LocationClient.Initialize(LocationClient.java:112)
at b4a.gsight.locationtracker._service_create(locationtracker.java:297)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:187)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:171)
at b4a.gsight.locationtracker.onCreate(locationtracker.java:46)
at android.app.ActivityThread.handleCreateService(ActivityThread.java:2572)
at android.app.ActivityThread.access$1800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5017)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
at dalvik.system.NativeStart.main(Native Method)