Moving frames

Hi there, I am new to Toon Boom and starting to create my first animation with it. I have blocked out my key poses so far but now I want to go in deeper and starting a breakdown pass I want to move frames around. However when I try to move more than one frame at a time it creates a duplicate of the frames I am trying to move and does not actually move the original frames. Am I doing something wrong and is there a way to move the frames without them duplicating?

Thanks Taz