UnMarshalException

I'm going completely bonkers over here .
I was going to upload my assignment today but something screwy is happening . My program is currently working fine when I use
http URLs and a web server for my codebase . And yesterday I had it working fine with file URLs .
But for some reason it's not working anymore : I get a crash when attempting to book . It's RemoteException and it occurs precisely at
database.modify(record)where record is DataInfo type .
The nested exceptions are UnMarshalException and NoClassFoundException . So it appears the server is not unmarshalling DataInfo record properly because it can't find the class ?
It works fine under my web server so I just don't get it . If anyone has an idea please let me know , that's all I can say .