SBL and Logitech speakers

[sevenal]

So whats the deal with the Creative Sound blaster Live audio card and 5.1
speaker set up.
I just installed a pc with a set of Logitech surround sound speakers "Logitech Z-640 6 Speaker Surround Sound System"
and the Creative card.
One rear Channel will not play,no matter what I try.
I saw this with the same audio card and the same speakers a couple of years ago,
but for the life of me I can't remember what was wrong?
I know the SBL card is 5.1 and the speakers are surround

Any Ideas??

Thanks

sev