Your tray may not be fitting properly or you are not putting enough solution in it. Have your dentist check this. He/she should also be monitoring your progress.

How long have you been using it? If it is only a few days, you may not see a difference yet. Also, you cannot eat or drink anything while the tray is in your mouth as this will weaken the peroxide solution.

I used this method when it was first available in the dental filed, almost 20 yrs ago. I had very good results and now just do touch ups periodically. I don't want glow in the dark teeth because it doen't look natural. I used Opalessence then but now I use NightWhite 16%. Sometimes I use 22% but that causes such sensitivity that i stay away from it if I can. Most products that dentists use are made of a carbamide and hydrogen peroxide mixture.

Hope this helps you.