Change Favicon

Hi I have a question about changing my forum favicon. I uploaded one a while back and it works fine, however I want to replace it with an updated version, but I can't seem to do that? I use the normal upload process like I did the first time, but It refuses to except the new one? Am I doing something wrong? Does the file name need to be different?

What error are you getting?

Hi there's no error message, I choose the new favicon.ico file to upload, click save and all is fine, however it just doesn't change.

edit

I cleared all the history and cache on the machine Im using just to make sure, but still old favicon remains
Also the Manifest image will not update either. ( can I send to you to change please )