I think the Piper allows you to encrypt the private key with BIP0038, right?
Perhaps you generated an encrypted private key? If so, I don't think that Litecoin-Qt allows direct import of BIP0038 encrypted keys. You'll probably have to decrypt the key first?
I think you might have just figured out the problem. I'm pretty sure I did check the option to encrypt it with BIP0038. How do I decrypt it so I can import to Litecoin-QT?