GOautodial Open Source Omni-channel Contact Center Suite

Hi,
I am trying to do agent to agent call transfer where agent A puts the customer on hold and clicks on the 'agent' link where he finds the agent to whom he wants to transfer the call then checks the box that says CONSULTATIVE and then clicks on dial with customer.But the problem is that the call is never transferred instead a msg is played saying that the extension is busy.

PS* local closer or blind transfer is working properly. But warm transfer isn't.

Please find the uploaded image. The channel box shows IAX2....(i don't understand how is that activated when I am only using SIP accounts.

I am using goautodial CE 2.1 on a IBM XEOX server with 8 gb ram. No extra software is installed