I've tried searching but no help so here is my problem:

Ok, I have a 98 sentra that I bought used with factory security system and "I think" keyless entry but it didn't have one when I bought it. I bought a remote of Ebay and now I can't get it to work. I do the key insert thing and the hazards blink twice so I'm good up the there. Then I turn the key to ACC and hit the lock button on the remot but nothing happens. I checked the battery in the remote and it is good. Would it be possible that I don't have keyless or that it is somehow damaged or am I missing something. Somebody please help!

I don't think mine will work with the key in the ignition, let alone when it is in the ACC position. I'm not sure on that, but I'll be glad to check...

You cant lock your car with the keyless entry when the key is in the ignition. I tried it one day when i was warming up my car and it doesnt work.

you might have to program the remote... i think it is as follows:

1 get in close the doors
2 lock the doors with the button on the door
3 insert the key in the ignition 5 times till the hazards flash
4 turn the key to the acc position
5 press the lock button on the remote
6 unlock and lock the doors with the door button
7 remove the key
8 get out of the car, close all doors and test.

if this doesnt work replace the batteries in the remote... this was my problem when i bought my car