have you made more than 100 sends since last backup?
No.
I copied the encrypted wallet. Put the original back in the safe. Unencrypted the copy. Put the wallet copy in an empty client. Sent some coins. Deleted the copy.
try running with -rescan parameter one time using your main (original) wallet, the transactions are saved in the wallet file so if the original didn't see one of them but has the priv key from reserve then it should appear and balance updated correctly
The original wallet is gone, and I tried rescanning the unencrypted wallet multiple times.
I'm missing something here. Doesn't the wallet key pool prevent this from happening unless you have over 100 transactions since you last backup??
Yes, if the pool isn't empty. But if you've never sent any bitcoins, the pool will be empty. (The client creates 100 *extra* keys when it creates a key for a transaction.) Because these rules are complicated to understand and easy to get wrong, I make my advice clear and simple -- unless you understand the rules exactly, always backup your wallet after sending.
I've sent coins before.
I copied the encrypted wallet. Put the original back in the safe. Unencrypted the copy. Put the wallet copy in an empty client. Sent some coins. Deleted the copy.
Are you able to find the transaction for the coins you sent in block explorer? (I don't need to see it, but if you can find it we can check to see if you have the keys for the account used to collect the change from that transaction).
Also, as others asked— how many times did you send+ hit getnewaddress since you made the encrypted copy? A few or potentially as many as 100?
I found it. How do I check if I have the keys?