There is no "unknown" tab. Are you referring to the "Unconfirmed" tab?
I think what you see under the Pay status column is periodically updated and at the time it was last updated, it will show "Unknown" when there was no payment transaction showing on the blockchain.
I would bet that if you click on your bet (the link for "details") it will give you a more up-to-date view for "Pay status".
Now it could still say unknown, even if it sent a payment. That simply means the web view lags the blockchain. The payment very well could have been sent. To find out for sure, click on the link for the Payment TX and it will show you the transaction in Blockchain.info. If it shows "unconfirmed (red)" then you have been paid, just that the payment has no confirmations yet If it shows a confirmation (blue), then you have been paid and there has been a confirmation. If there is no transaction found, then SatoshiDICE hasn't sent it yet.