91 Jetta

hey everyone

i picked up an '00 S2000 a few months ago with a 2-way Viper alarm installed. i'm not able to check what the exact model is at the moment but i'm not sure this problem is model specific..

- sometimes the door will not lock when the lock button is pressed
- however the door unlocks and car will disarm properly always
- even if the door doesn't lock, the alarm will arm properly
- does not appear to be any pattern in when the door does lock properly and doesn't. sometimes it'll be good for a week, sometimes 3 weeks, sometimes 3 days. then it'll go on a streak of not locking when i press the button, meaning i have to use the key manually.

i hope this makes sense. has anyone seen anything like this before?

thanks!