Chainsaws

Husqvarna advertised an extended warranty program at Lowes with additional purchase of oil. According to Lowes, to activate the warranty, I needed to send a copy of the receipt with my registration to Husqvarna. I did so - and it came back - moved / unknown - return to sender. In FAQ I saw someone else had exactly the same problem - but no solution was listed. Please advise how I should proceed.