I don't think it's because you did not buy the blank from them, I had a key press at work that I wanted more spare keys for the team, I took my key to the store and had 5-8 new keys made up, from blanks that they supplied. 2 did not work, and 2 you had to twist and turn a little to get them to work....the rest were fine. All cut by the same person, there and then using the same original key to cut from.
I'm not sure I would be using any glue.....if it were to snap off and you could not get it out.....how much is a new ignition ?????
Best of luck