Android Force close in ICS but not in Gingerbread

Android Force close in ICS but not in Gingerbread

I have a problem in one of my activity, is that when I test my app in
android Ginberbread 2.3 all going great. But when I Test My app in Android
ICS or Jeally bean it force to close, in a last activity, and this is the
error show me in the debug:
08-11 18:46:55.666: E/AndroidRuntime(16107): FATAL EXCEPTION: main
08-11 18:46:55.666: E/AndroidRuntime(16107): java.lang.RuntimeException:
Unable to
instantiate activity
ComponentInfo{com.prueba.bibliotecaappprueba/com.prueba.bibliotecaappprueba.DetallesActivity}:
java.lang.NullPointerException
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1973)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2083)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.app.ActivityThread.access$600(ActivityThread.java:134)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.app.ActivityThread$H.handleMessage(ActivityThread.java:1233)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.os.Handler.dispatchMessage(Handler.java:99)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.os.Looper.loop(Looper.java:137)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.app.ActivityThread.main(ActivityThread.java:4697)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
java.lang.reflect.Method.invokeNative(Native Method)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
java.lang.reflect.Method.invoke(Method.java:511)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
dalvik.system.NativeStart.main(Native Method)
08-11 18:46:55.666: E/AndroidRuntime(16107): Caused by:
java.lang.NullPointerException
08-11 18:46:55.666: E/AndroidRuntime(16107): at
com.prueba.bibliotecaappprueba.FileCache.<init>(FileCache.java:17)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
com.prueba.bibliotecaappprueba.ImageLoader.<init>(ImageLoader.java:33)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
com.prueba.bibliotecaappprueba.DetallesActivity.<init>(DetallesActivity.java:50)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
java.lang.Class.newInstanceImpl(Native Method)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
java.lang.Class.newInstance(Class.java:1319)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.app.Instrumentation.newActivity(Instrumentation.java:1023)
08-11 18:46:55.666: E/AndroidRuntime(16107): at
android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1964)
08-11 18:46:55.666: E/AndroidRuntime(16107): ... 11 more
08-11 18:47:02.604: D/dalvikvm(16143): GC_FOR_ALLOC freed 28K, 2% free
12847K/13027K, paused 16ms
I dont know why it works in Ginberbread, but not in a ICS, please help me!
and thanks.
I've been looking for help in others answers but it doesnt help me :/ thanks!