The bridge documentation can be found here:
http://coppermine-gallery.net/demo/c...ng_steps_start
I have vBulletin 3.6.8 installed and Coppermine 1.4.12. They are successfully bridged.
My suggestion would be to make sure the paths to your cookies are set up exactly the same. For example, in vB I have my cookies set to "/forums/"... make sure in Coppermine it is set to the same and not just "/".
Gandiel