How to transfer addresses from Satoshi client to MultiBit?
Notice that your private key retrieved from the Satoshi client begins with a K. According to the List of Address Prefixes, that means the key is exported in compressed form.

MultiBit's export file saves private keys in uncompressed form. Private keys in uncompressed form begin with a 5. 

You can divine the uncompressed key using Bitaddress's wallet details page. Just look for the private key that begins with a 5. It's the private key that has a QR code next to it.

Repeat the latter part of your steps, adding the uncompressed key to the export file and then importing that file.