Issues equipping my waist

[Kuuuuuuuuhar]

I have the waist, it was equipped for long time. Today it randmly got unequipped and I got a mail from the server with that waist saying there were issues equipping it. I took my waist from mail and when I try to equip it, it fails saying I cannot equip one more of it, but I do not have it equipped.
Can anyone please help?

[Shred92]

You probably have it socketed with a gem that you can only have one of. Change the gem for another one.