Factory Alarm - 99 Silverado

Just installed a Crimestopper RS900 in a '99 Silverado, no problems. However, the remote lock/unlock doesn't arm/disarm the factory alarm. The factory remote allows you to remotely lock the doors and it arms the alarm. The RS900 will lock the doors but not arm the system. I tried to take the neg output from the lock (before it got to the polarity inverter - Silverado locks are positive and RS900 puts out ground pulse) and send it to the doorpin as the wiring diagram I downloaded stated that a ground pulse from the doorpin at the same time you lock the doors would arm the system but it didn;t work - in fact it messed up the locks and they would immediately unlock after a lock command. Has anyone figured out how to incorporate factory arm/disarm with door lock/unlock on these GM vehicles? Thanks for your boundless wisdom!

Installing same in a Trailblazer tomorrow, but it uses the GMDL1 module which handles locking and arming automagically so it won't be an issue (I hope)!

OK, persiverence (sp?) always pays off! Spent an extra hour and went back into the whole thing and discovered I had the wrong doorpin wire. Further testing and removing the driver's kickpanel revealed the REAL tan doorpin wire. Tapping into it with the Crimestopper RS900 rearm wire works great. Even rearms the factory security during a remote doorlock. Excellent! Now to figure out how to start the rear defogger using the trunk button!