Can't move my camera in Viewport.

Im a bloody beginner in Unreal and i have a problem with my camera movement (right mouse button).
Yesterday i was playing arround with the terrain tool and today the camera won’t work. I can move up, down, left and right with the MMB, but i can’t rotate.
LMB to zoom in works also fine.

Any ideas? It’s really frustrating… at least it’s not my first bug in Unreal.

I hope my english is understandable. :slight_smile: