Yahoo on my Blackberry shows MSN contacts as offline

[jackmac]

Anyone any idea on this one? I donwloaded Yahoo on my Blackberry, then set up a contact on my computer in MSN. On my 'berry. it shows me as offline on MSN, yet MSN on my computer shows me as online in Yahoo. If I send a message from the 'berry to the computer MSN, it shows up on the computer, yet replies to the Yahoo on my berry won't. Doesn't make sense... anyone any ideas?

Anybody managed to get Yahoo on their Blackberry to connect to MSN on a computer?

TIA

Jack