Signatures not working for all users in forums

I am using v6.01.15 with the Darken theme

All of the users including myself cannot add a dynamic image as a signature

For example:
a picture from photobucket using the [IMG] link

i click save settings in my profile settings and wen it refreshes, wat i just put in there is gone and no sig shows up

can anyone help me out?

thanks for your time,
-Chuck