I think you need to change your tris settings. Unless I missed something?

You Have
Code:
       TRISA=0          'All A Port outs
       TRISB=15         'All B Port Ins
       CMCON=7
        
       LED VAR PORTB.0
TRISB = 15 = %00001111 which means you have portb 0 - 3 as inputs

Try Trisb.0 = 0 or trisb = 0