one string as base name for different classes

It is getting a little bit crazy now.
I had it all working like a charm and was super happy. And suddenly out of nowhere it stopped working again. Maybe because I restarted the engine, once ??
Now the Cast To SoundWave and Cast To AnimSequence faile because the paths are none.
Before the restart the paths where right and the Cast To worked.
Do you have any idea about this ?
kind regards
Ingo