I have an 8 year old Intellisense 800L Alarm system. Just extended the house want an extra keypad in the garage. Found compatible keypad by TATE company online. Gave it to my fitter who also installed 2 more sensors. However he had a problem and was unable to make the keypad function. It lit up you could see the zones but not able to key in code. I checked the manual online this system is definitely able to carry more than 1 keypad. Please help me if you can!!!! I dont want a new alarm system - Out of budget!!!!!!!