Why Won't My Signature Show?

So, I copied and pasted the Image URL to a gif image I wanted and clicked preview. Everything looked fine. So I clicked "save," but everytime I posted my image would not work. So then I looked up why and saw: "You have to click the "Always allow my signature in my posts." or whatever. So I did that, clicked save again, and it STILL won't work.

Admin Control Panel >> Users & Groups >> Users >> User Options >> Allow Signatures: All Members

I also have the same problem on my forum. I am unable to view my signature.
It would be much appreciated if any of you could help me with my problem.