I am new to FS and I am trying to set 

sip_from_user in the B leg   to 111222

 sip_from_display in the B leg   to 98762

 sip_contact_user in the B leg   to 98762  

by using the export variable in the dial pla but I am unable to get it working

<action application='export' data= "sip_from_display=${Num2}"

The outbound Invite the SIP header is not changing to the value set in variable Num2 . Can anyone help ?