I am trying to send the conference pin through dial command using D option, but it is not working. I am getting error message saying ‘invalid pin’.

My setup :
- I am using two Asterisk server
- 1. Normal Server (Server-A)
- 2. Conference Server (Server-B)
- All users are registered on Server-A
- Users 101 and 102
- 1234 is conference room number on Server-B

Call Flow:
- Through Asterisk Manager using “Originate” command i ll make a call to 101

        $response = $asman->Originate("SIP/101",

       - After successful connection, moving to an extension 'confcall'
       - In confcall extension , i ll calling conference number on Server-B
          exten =>   
         exten => _[0-9].,n,Hangup

Both asterisk server version - 1.4.4

Thanks in advance,