Duplicate data

[pam0566]

I have a form named "frmvehicles" in that form is a field "vin". it is 17 digits long, and auto tabs to next field. I want something that will tell me if the 17 digit vin number has been IN My system before, and if so pull up a form Called FrmHistory. I need the system to ask "Would you like to continue" and a yes or no. we do have reasonss were we could enter the car again from a new seller. so far everything I have tried is not quite right... i dont want to force no duplicates, because it could be allowed.. just want to question, and if need be pull up a history form (list of vehilces with that same vin) in a new window.

Any ideas? i am a newbie really, been a while since i have done this.

Thanks!!!!!!!!!!!!!!