Hi @karam,
Thanks for your patience. We were able to successfully test a number of Rex Units along with the latest version of the Tobii Controller SW, so no problems with compatibility.
I wonder therefore if you are sure to have installed the drivers service package @ http://www.tobii.com/xperience/support/downloads/ (at the bottom of the page)
If you have, and indeed if the issue still persists on another PC (if you could try that) then I am afraid we will need to issue a repair for your device.
Could you kindly go through these last steps and let me know how you get on. Thanks.