Whitening strips not working!

So they worked for all my teeth but 1... I have a tooth that's partially fake because I chipped it... the fake part is white because I planned on whitening my teeth but the other REAL part of that tooth won't whiten! any1 else experience anything like this? iv cut down my strips and just applied it to that tooth but its not doing anything... please help
Whitening strips not working!
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