Nissan Repair: keyless entry, nissan altima, brain box

Question
I lost my key to my 1998 nissan altima GLE.  a locksmith came and made a new key but i still cannot start the car because of the alarm.  i tried to use the valet button to turn the alarm off.  i did this by turning the ignition and pressing the button but nothing happened.  the alarm is not a factory alarm it is a off the market alarm.  what can i do to disengage the alarm so that i can start the car?  P.S. the key that i had made does fit in the ignition.

Answer
The alarm should have a valet switch on it.  The brain is under the dash on the drivers side.  That is where they usually install aftermarket alarms.  Also, you can go to an alarm shop of if you get the brand and model off the brain box you could look them up on the internet and get another fob with the correct frequency.  If all else fails you can remove the alarm.