[jboss-user] Message Driven Bean config

I have a simple ejb application where I have one MDB which reads from a TIBCO EMS Queue and persists the message in db. I have defined MDB pool size as 30 still I see only 2 readers on EMS Queue. Any ideas, I thought if there are 30 MDB instances there should be 30 readers on EMS Queue? (for running this experiment, queue is always initialized with 10000 messages so for the duration of experiment, MDBs will always have some messages on queue to read). Any help would be much appreciated, as functionally application is behaving perfectly, but performance is shabby. Thanks and Regards, Sid.