How do I load songs with home sharing and load ...

Hi there

When I try to load songs onto my Mac it says it has been associated with an Apple ID or something and can't be done for 90 days. I have home sharing on and this still happens. Also, I am trying to find a particular song I have purchased, in my purchased list and it's not there. However, when I go into the store and search this song it is listed as purchased.

Thanks in advance