GPRS card streams with BT, but not with CF

I use an Audiovox RTM-8000D CF card to connect to the internet with TMobile GPRS when I don't have access to a wifi network. For some reason, when I have the card in my X50, it works fine with PIE, but will not stream audio in either RealPlayer or GSPlayer. However, when I put the card in a laptop, and connect to the laptop via a Bluetooth USB dongle, I can stream just fine. I don't think there's a problem with the X50 CF slot, as I can play movies from a CF card, using BetaPlayer, with no issues.
Any connection gurus have any idea on why the direct connection (Audivox card in X50) doesn't work, but the indirect connection through the laptop BT dongle does?
Mick