Bitcoin-Qt wallet shows outgoing transaction as "Offline (0 confirmations)"
Offline means that the transaction hasn't been sent to the network, that is, it's not in the memory pool of any other node.

Unconfirmed means that the transaction has been sent to the network and exists in the memory pools of many other nodes.

If the wallet is out-of-sync, that would be the reason it's got 0 confirmations. Even if you did have a confirmation, your node wouldn't know it since the transaction would be in one of the newest blocks.

If the transaction is not on blockchain.info, there's a very good chance that it hasn't been sent. You should probably resend it using the instructions found here.