No display of the clip while moving them in the timeline

Hey guys,

somehow I cant see the clip anymore when im moving it in the timeline... its really hard to describe the problem. But usually if you move a clip you see a preview of the part it will cover in your timeline. Currently im can´t see that anymore but instead i do get to see a timecode showing me how many seconds im voing the clip to the left or to the right.

Maybe you guys can help me figure it out?

Cheers.