Adding Sip Header

I am using command SIPADDHEADER but it is not setting
This is the code. Please help what is wrong in it.

exten => _X.,n,NoOp(${SIP_HEADER(Call-ID)})
exten => _X.,n,Dial(SIP/${EXTEN}@,U(sip-trunk))

exten => s,1,SIPAddHeader(X-GPCallID: ${ACDCallID})
exten => s,n,NoOP(${SIP_HEADER(X-GPCallID)})

THis value should be set in GPCallID 50e5ea9c3baaed52561ad3033f3d9272@

But on net line on NOOP is shows blank


I wouldn’t expect the function to see additional outgoing headers.

Did you check the actual outgoing SIP Invite?