Can I Not Use my GC Uniform For Glamour?

[CommandoCat64]

Hi, my character is a lvl 52 dragoon, lvl 20 pugilist. I just found out I can buy an Order of the Twin Adder uniform. It requires level 20, I'm level 20, and all classes can wear it. However, when I put it on a glamour plate, it says that it's incompatible for glamour with my race, class, gender combo? Why is this? I'm a member of the same GC. Any help would be appreciated.