I'm pretty new to AE so I don't know much. I'm using a template, and when I try to use a .png image with transparency, it won't let me extend it in the timeline for more than 2 seconds? I can use other images such as .jpg's just fine. Never seen this before, any Ideas?
Are you importing the png from a folder that has more png images? If so, it may be that AE sees that as a sequence and imports all images as a clip. That would explain why you can not extend the layer, other than that there should be no limit.