SAPGUI transaction doesn't open in NWBC html client

We start the html version of NWBC from sapgui. This opens and runs the webdynpro applications like expected.
In my menu (pfcg) there are also transactions which open a sapgui screen.
The programm is started which i can see in the debugger, but it doesn't open a screen. I only see a grey screen.

This is for all sapgui transactions the problem. From sapgui the transactions starts normally.

What can be the problem?