Recently installed a home security system using a texecom Veritas panel with a Pyronix deltabell plus illuminated bellbox along with a handful of sensors. System works great however after checking over the system after completion and all working as should I have since noticed the backlight on the pyronix bellbox no longer illuminates when it's dark. If I go into engineering mode and test the strobe and then turn off the bellbox now illuminates. Could this be a faulty light dependant resistor or is there something in the installation I have done wrong? Any ideas would be greatly appreciated. Thanks