Using an old backup wallet

[WhitePhantom]

Quick question for those more informed than me.  I had 38 BTC in a wallet backed up on November 7th.  Today, I loaded that wallet up in Bitcoin QT and sent 36 BTC.  I then deleted the wallet and put my normal wallet back in place, assuming my November 7th backup was all I needed.  However, I then put the November 7th wallet back into Bitcoin QT and the balance is zero instead of the expected 2 BTC.  The 36 BTC transaction from today also does not show up in the transaction history.

To see if rebuilding the block chain in my client helps, I copied the November 7th wallet to a fresh install of Bitcoin QT on another computer, but it will be hours before the block chain is done downloading.  What would you say I should expect to find after it's done rebuilding?

The reason I ask is because I remember reading once that when you send part of your BTC balance, the whole balance is sent and then part of it is sent back to you.  Would using the November 7th wallet make it so I don't have access to coins that the more up-to-date wallet I deleted contained?

Thanks in advance!



Edit: Well, the block chain finished rebuilding and my 2 BTC are back.  Woot!

[BookLover]

https://en.bitcoin.it/wiki/Key_pool 
Basically you have 100 pre-generated addresses in your wallet and you use them when you create an address or send a transaction.  As long as you haven't used all 100 of these addresses since your last backup it will still be valid.

[WhitePhantom]

https://en.bitcoin.it/wiki/Key_pool 
Basically you have 100 pre-generated addresses in your wallet and you use them when you create an address or send a transaction.  As long as you haven't used all 100 of these addresses since your last backup it will still be valid.

Awesome, thank you for the insight.  Very good to know.

[Abdussamad]

You can just start bitcoin-qt with the rescan option (-rescan command line switch I think) and it will find the missing transactions. That may be faster than downloading the whole blockchain again.

edit: yeah that's it:

-rescan                Rescan the block chain for missing wallet transactions

Place the November 7th backup in place and try the rescan.