incorrect pin message

I bought a 2001 cl about a month ago. Back then the navigation system was working fine untill I changed the new batery. I tried to enter the pin and I got the incorrect pin message.
Any help or input would be appreciated.

Call the dealership that it was bought from new and give them the VIN# and then tell them you need the PIN for the navigation. Maybe you have the wrong one.

Thanks for your suggestion Whtteg. I found the problem. Because the previous owner changed the nav dvd unit. without written down any new code in the code verification. So, it is a different code.
I have to pulled the unit out and get the serial#. It's work now.