Android : Getting java.lang.NoClassDefFoundError when using android-betterpickers library

Whenever I try using a Fragment that utilizes the android-betterpickers library, I get the following error.

I have my projected pointed to the android-betterpickers as a library for my project. Anyone know what may be going on here?

08-10 02:06:39.152: E/AndroidRuntime(2628): java.lang.NoClassDefFoundError: com.mavdev.focusoutfacebook.fragments.addablock.selecttime.Fragment_time_addblock
08-10 02:06:39.152: E/AndroidRuntime(2628):     at com.mavdev.focusoutfacebook.fragments.addablock.Fragment_AddaBlock.displayView(Fragment_AddaBlock.java:224)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at com.mavdev.focusoutfacebook.fragments.addablock.Fragment_AddaBlock.access$0(Fragment_AddaBlock.java:211)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at com.mavdev.focusoutfacebook.fragments.addablock.Fragment_AddaBlock$ListItemClickListener.onItemClick(Fragment_AddaBlock.java:293)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.widget.AdapterView.performItemClick(AdapterView.java:298)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.widget.AbsListView.performItemClick(AbsListView.java:1100)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:2788)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.widget.AbsListView$1.run(AbsListView.java:3463)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.os.Handler.handleCallback(Handler.java:730)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.os.Handler.dispatchMessage(Handler.java:92)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.os.Looper.loop(Looper.java:137)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at android.app.ActivityThread.main(ActivityThread.java:5103)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at java.lang.reflect.Method.invokeNative(Native Method)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at java.lang.reflect.Method.invoke(Method.java:525)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-10 02:06:39.152: E/AndroidRuntime(2628):     at dalvik.system.NativeStart.main(Native Method)

I am just extending one of the classes of android-betterpickers from one of my Fragments, shown below, just not showing the other functions like the onCreateView in the Fragment:

public class Fragment_time_addblock extends Fragment DatePickerDialogHandler {


@Override
public void onDialogDateSet(int reference, int year, int monthOfYear,
        int dayOfMonth) {
    // TODO Auto-generated method stub

}


}

What can I try to fix this issue?