Here are some questions that may help:

1. Are your using Access 2007 or 2010? If you're using an older version, it won't open accdb files.
2. Can you run Access the normal way (interactively) and open the file successfully?
3. If you can open it when using the interactive method, what happens if you specify the complete path to the accdb file in your OpenCurrentDatabase call? It's very likely that without the full path Access' current working directory won't be the one where your Perl script and accdb file are located.