Does anyone have an idea what is going wrong?
Chances are the transaction with 1.0 BTC hasn't yet confirmed -- perhaps no fee was paid so it will take a bit, maybe 24 hours or so. Blockchain.info knows about the transaction because it was "online" at the time the transaction was broadcast. Your second (new) wallet might not know of the transaction because the client with that wallet was not running when the transaction was broadcast.
The 100 BTC transaction probably has already confirmed and thus that's why the client with that second (new) wallet shows that only.
So check in Blockchain.info for the transaction that has the 1.0 BTC and see if it has any confirmations.
If it does, and your second (new) wallet still doesn't show it, make sure your client has connections and synchronization has completed.