Neo Key Booting Problem

[Aden]

Recently I got the Neo Key external mod installed in my American PS2. However, when attempting to boot up silver-backed backup
games, my system froze at the
"Loading" portion of the GameShark booting process. Thinking that there was
something wrong with the modchip, I brought it into the store that installed
it. They said that the Neo Key cannot run silver backed CDs, and that I can
only play gold backed, green backed, blue backed etc. However, other sources tell me that the Neo Key can boot up any color CD.

Is there something I am doing wrong in the bootup process, or do I just have backup CDs that won't work?