Mysterious difference of mapping on Integer on windows an Bi

[jadtn]

Hi,
I have a jboss4.2.2, which run under windows for dev and linux for production.
All my jboss configurations files are same under linux (unbuntu) or windows.
I ve a strange difference
My EJB is with a int field;
I use a query ( Query q = em.createNativeQuery(request);)
Under windows I get my field as this

photoId=((Integer) rs[8]).intValue();

But it doesnt works under linux and i need to get a BigInteger.

photoId=((java.math.BigInteger)rs[8]).intValue();

So temporarly i do:

if(rs[8] instanceof java.math.BigInteger){
 photoId=((java.math.BigInteger)rs[8]).intValue();
 }else{
 photoId=((Integer) rs[8]).intValue();
 }

There is anybody who have an idea?
Thanks

[jaikiran]

Which version of EJB? EJB3 or EJB2.x? And which database server and which JDBC jar file and version are you using? And please provide more details about your application including any entity mapping (either through xml or annotations)