Haven’t done any work with DB2…so:-
Usual generic causes of this are:-
You haven’t installed a DB client and any, if needed, necessary config files on BOXI.
DB Middleware is unsupported by BO version.
You haven’t installed the BO data access pack for DB2.
You have not set up the connection on the server, if needed by that RDBMS.
Installation of Crystal server side can cause issues.
This may help:-
https://bobj-board.org/t/105873/2
Mak 1 
(BOB member since 2005-01-06)