autopilot not working

[Ddg1500]

I found out recently that the autopilot system is not working, like when i switch on all the necessary nobs in the front cockpit at the autopilot panel, the a/p reference isn't lighted on as past, and there is also nothing happening when i press the nws button, what is going on? could someone give me an idea

[AH_Solid_Snake]

Did you have all 3 SAS channels on?

[Ddg1500]

yes 

[Ddg1500]

i just restart my sas and autopilot is still not working

[near_blind]

What mode are you trying to use? What speed and altitude are you at while trying to engage the autopilot? Are you level? climbing? diving? I'm not sure what knobs you'd be rotating, but you've got A/P master set to on?