PreferenceActivity not showing twice on android

i've a PreferenceActivity which works perfectly the first time i launch it.

But if i close it ( with the back button ) and then i re open it (开发者_如何学Python through a menu click in the main activity ) then i get a black screen. There is no preferences at all..

I can't figure it out why it should not working.

It seems all the code is being called normally as the working one but no preferences are showing on the screen.

Did someone had the same behaviour ?

Here is a sample project that demonstrates the use of PreferenceScreen and does not suffer from this problem. Perhaps you can compare your implementation to this one to see where things differ.