you have done wrong in this design.
you have made a ground plane under the dielectric but in CPW antenna there should be no ground under the substrate. Ground plane is use to be present on the both side of the microstrip line. In your design the rectangle 3 and rectangle 4 should be the ground plane and these ground plane should be conduct by excite them.
i tried to do correction in your design and i have assign the port in your design.just have a look on this an dtry to understand that how i assign the port
i hope it will helpful for you