Why can't I drag my images from outside the window/in Library to the stage?

I just started up my storyboard pro, and I can’t drag my library files(images like jpgs or pngs) to the stage on the left. I cant drag from my file navigator to the storyboard program either. Please help ASAP! This is for a test.

Update: I can’t even draw in it. I have no idea what to do, guys.

… Problem solved. I just restarted the program.

But what did I do to make it do that??