Clarence

Hi there, I have a MacBook and I am trying to insert a line break on an activity in an activity diagram. So far I have had no success. I have tried every possible combination I could think of (cmd + return, shift +return being the most common ones) and it just flat out refuses to create a line break. I was wondering if this feature exists for Macs, and if so how would one go about using it. Cheers, edoreld