Help!!

I have been trying to put a pic up on the chat avatar(like so many others) and I just cannot for some reason. It keeps saying this...The chat avatar image you uploaded was not a valid image file format. Any ideas why or how to correct this? Greatly appreciated!!!

I know the file can't be too large either. Maybe try resizing.

Also, mine never seems to change right away. It takes a few minutes.

Thanks you guys are great...I did it finally!!!