What version of Plogger are you using - version 2 or Beta 3? Also, is this a newly installed gallery or an existing install that previously worked?
The current Beta 3 version available for download does not work with SAFE MODE enabled on a server. However, sidtheduck indicated in another thread that the current SVN trunk has a work-around for safe_mode that should solve your problem.
If you try the trunk version, you have to re-install (not just upgrade) since it needs more information to connect via an FTP / PHP connection. Try to run the _install.php file again from the trunk (it won't change any of your database).