Enable live view for Canon EOS 450D

Hey guys, I was searching a solution quite a while now but can´t find this specific topic in here.

I connected my Canon Eos 450D to my Mac and it was recognized by iStopmotion, so far so good.
But instead of a live view the display just shows a short text which says that the camera is suitable for live view but you have to activate it in the bar below.

But I can´t find any button or option to activate it! Where is it?

I would appreciate a quick answer, please help!

Hi Luke,

sometimes the cameras behave strangely. Please make sure you remove the memory card since this can sometimes cause issues. The button is on the top right not on the bar below. Sorry about the confusing description.