Custom shapes not working

I'm trying to create multiple custom clouds, on my 10th one, every time I go to click on the button to insert a custom shape, it will let me select the image file, but it does not appear in the shape gallery. Is there a limit to how many custom clouds that can be created? I just created a custom cloud shape a few minutes before my failed attempt, so I don't think it would have anything to do with my computer. I can create clouds with the options that are already in the shape gallery, I'm just wanting to customize

never mind...I was able to do it on a different computer, but I still don't get why it was working on my laptop just a few minutes before and now it doesn't, even after rebooting. Oh well :)

Could you please send me custom shape picture that didn't show up in shape gallery? May be something is wrong with it?