No Ds and Rs from other BBs

Hello. I used to get notification on my boyrfriend's BB IM status. I would get the usual Ds and Rs. For the past week or so it is a crap shoot. He has a new touch screen BB from Verizon.
We notice it usually happens when he is not actually USING the BB - like charging or the screen is LOCKED. Then I only get a "tick" mark that I have sent it. Nothing says it was delivered.
Is there a setting we should check?
Like HOLSTER or something?
Is it a system problem or is this normal?
Should we take it back to Verizon? Or is this just plain operator error and it is on a MODE or actually OFF?
Please help. Thanks a million. Dot