Intruder Alarms

Hi my home has been fitted with a scantronic 9651 system, it has p.i.rs in all down stairs rooms. The front and rear doors have surface mounted contacts. When I set the system and leave via my front door the alarm continues to beep and will not arm once I close the door. This has happened before and I was advised to replace the door contact which i did, this solved the problem until now! The same thing has happened again I have checked the contact and everything seems to be OK with no loose wires. The contact is grade 2 with a small circuit board inside, it also has a small spring tamper mechanism. Can anyone help? regards Steve

Hi i had a scantronic 550r wireless alarm system fitted 18 months ago,great but it has gone off 15 times since then and every time it flashs rf trouble ,today it has been flashing all day .i am now to frighted to set the system , please help