Can't add more than 11 clips/videos? Help!

So in my editor I make videos for my band and i have 11 videos from my camera but have edited and trimmed them. Whenever i go to add another video a red circle with a line through it appears where my mouse is and won’t let me place the clip. I only have 2 mins of video because of this and that will not suffice. Please help!

Save, Close, re-open.

Happens from time to time to us all.