[Typo3] extending julle_events

[jim]

Hey all,

I'm trying to extend julle_events to include some other fields for the 
participants registering, etc.

I've created a new extension extending the participants table, and 
installed it etc, making the necessary changes to the participants table.

The fields are shown in the backend fine.

Thing is when i go to register i get this message:

|Possible failure in getLLFromString - not an EXT?||Possible failure in 
getLLFromString - wrong namecount?|TYPO3 Fatal Error: Extension key "" 
was NOT loaded! (t3lib_extMgm::extPath)

I haven't really got any idea what this is going on about.. any ideas? 
or where theres any information about extending julle_events?

thanks in advance,

Jim