I've got an exception and i don't know why

I'm new in ejb so if one of you can help me

my id is an int in my classes
in my mySQL dataBase an INT(11)

The exception:

EJBException:; nested exception is:
javax.ejb.EJBException: Internal error setting parameters for field id; CausedByException is: Type Conversion not supported: VARBINARY

An idea?

what's VARBINARY?

thanks