Hi Aman, I have not used WCF Clients so this is just speculation. However, you indicated that you were able to record a service using HTTP traffic. I would start by verifying that there are no SSL handshake issues.
One approach would be to add a debug directive (-Djavax.net.debug=all or -Djavax.net.debug=ssl) to your Workstation.vmoptions file (if recording through Workstation). Make the change, stop/start Workstation, and after trying to record a transaction, open up the Workstation.log. Look at the handshake to see if the WCF client and DevTest settled on a suitable encryption routine or if the client or server terminated the handshake. It may be that WCF is expecting a certain certificate or encryption that is not in DevTest's default keystore.
Note: use caution of you copy the directive above as the "-" character may convert to a different ASCII char when pasted into the vmoptions.