Blindxfer does not work

I can’t seem to be able to transfer calls with the # key or any other key that i set with blindxfer. My extensions look like this: exten => 11,n,Dial(SIP/11,30,Ttr). I’m using x-lite sip clients and analog phones conected to a TDM400 card. I can only transfer calls with the analog phones flash button. When I press the # key on the phone I just hear it in the other end. I have asterisk 1.4.22. Why doesn’t * transfer my calls?