I want to place a blue band at the foot of a clip so that I can write text on it. I have done this successfully several times and cannot understand why I now have a problem.

I have got as far as inserting a generated media frame above a video clip and choosing solid colour --> EPC. I have ensured that Maintain aspect ratio and Stretch to fit Frame are both set to No. But as I drag the the colour down from the top, instead of the colour being dragged uniformly down the frame to reveal the underlying clip, the colour band comes in from the edges until I end up with a small coloured square in the middle at the bottom of the screen instead of a full-width band across it.

Please bear with me - what I can't do must be obvious to experienced users. I would appreciate any help - Bambino