Hi,
level1 = RCREG
portC.1 = level1 'i want to dimm led on port c.1
RCSTA.7 = 0
RCREG is the hardware USART receive register (SFR). You are trying to dump its value (dimming value) to a Port PIN C.1 . You should use a PWM to achieve this. Your checkdmx routine waits for a valid address and then grabs the byte being received. Use the Hardware PWM unit to make your life easier.