CADFEKO Error 3849 Wrong medium specification

Hi EveryOne,

I am looking to cater this error on CADFEKO Error "3849 Wrong medium specification" which I am getting while desining a microstrip patch antennas. Can some one kindly assist on this

Structure of antennas involves following layers

Ground Plane Finite which is Perfect ELectric Conductor
Air which is formed by Cuboid defining it as substrate which has permitivity 1 and tanlosses =0
then we do have substrate with thickness of 0.762 na having value 3.3.
On top of strip, there are three patch which are microstrip feed with three different ports and three different sources.

Thanks
Sunny