JPA + enum == Exception

I'm trying to use enum's in a database, but the java guys are telling me that they are having problems with inserts …
readingfrom the database isn't a problem, but there appears to be an issue with converting from string -> enum when
savingit back again … 

they are using JPA2 / EJB + Eclipselink … on the jboss side, we are running the latest jdbc driver …

considering postgresql has always supported enum and extending types, I think they might be missing something, but I
can'tthink of what to suggest … 

Is there a doc online I can maybe point them to about doing this … ?