Android :: PreferenceScreen - Intent - Element Throws Exception

I've got a probleme with an exception, but I don't know why I get this exception.

The project is about implementing an AbstractAccountAuthenticator with an AbstractThreadedSyncAdapter to sync certain data on a server with a content provider.

I made everything and both adding accounts and syncing is running without any problems.

Now I've tried to add a Preference-Screen just like suggested in the android reference (search for AbstractAccountAuthenticator, it is explained there) via xml like this:

autenticator.xml:

CODE:..........

The Preference-Screen-xml looks like this:

CODE:.....................

The screen is promted how it should be, but and that is the problem: When I click on the PreferenceScreen with the intent it leads to a crash of the system (both in the emulator and my HTC-Desire).

Logcat says:

CODE:..............

Here the part of the manifest, where the activity is defined:

CODE:.......

The whole test-code (it is my project on the essentials to find the problem) is to find at googlecode (http://code.google.com/p/ cleanproject/source/browse/) (Eclipse-Project)