Are you near a lexicon of power?
Are you trying to put a major in a minor slot or minor in a major slot?
Have you actually purchased a glyph off the AH or crafted one yourself through inscription?
You're really not giving enough information for us to work with. Normally someone with my... er... reputation for being a jerk would be all over this post flaming it left and right, but dang dude you're so lost I can't help but feel sorry for you. Give us some more information and maybe we can figure out why you can't get a glyph.