I have the same problem. I was looking at the bridge script, nextbb.inc.php and it looks as if coppermine is expecting a different interface than the bridge script is providing. Looking at the bridge scripts that Coppermine provides as part of its distribution, the interface is object oriented, with an cpg_udb class being derived from some base class provided by Coppermine.

The bridge script that is linked to from the Extensions page here appears to be terribly out of date and incompatible with the latest version of Coppermine. It needs to be rewritten if there isn't a newer version already out there. If there is, the wiki needs to be updated. I'm going to try to either rewrite the bridge myself or write an adapter for it.