can any one help ive got a logic 4 panel on my shed  which is wired to a sab bell box as follows 
bell box                   logic 4 panel 
tamper return -        t=tamp return 
hold off con -           a= 0 volts 
hold off con +          d= 12v +  
trigger-ve                b=trigger 
the problem is when the alarm is triggerd the sounder is screeching not sounding but if i tamper the bell box it is sounding so i think either the one of the connections are wrong which im sure are not or can the sab work with a scb panel or the panel is knackerd  any suggestion please  
kind regards barry