Can anyone explain what would happen if I created a wallet in 2010 and someone sent coins to the wallet address, gave me a tx number that I stuck in and hit receive, shut the wallet down and left Bitcoin demon running ( It probably didn't sync with the network) and went to work. When I got home the power had been off and the computer was off, I never had it back online since then. I looked on the block chain at old addresses and don't see that amount around the time it happened.
If some one sent the coins to that walle, then there should be the coins, even if the wallet get down or get offline, the bitcoin network keeps running, so there is no reason to not see the coins on the addy, unless the transaction get a double spend.
Maybe when you take a look at that block you search for a wrong addy, bitcoins doesn't disappear in the air, so if that transaction was really made, it should be listed in the blockchain.