[Achievement] Sharing is Caring - Issue

Hi all.

I’ve a problem with this achievement (upload a file to your file share). When I try to upload a local file (my pics or film clips) says “You need xbox live gold account to do it.”

What does this mean? I have the gold account, I play wargames (in party = gold) every day…

Thank you very much, and sorry for my poor english! ;>

Please, help me