waveguide to microstrip Measure s-parameter

Hi,
I am designing simple rectangular waveguide of some 50x100. Then i try to catch microwave signal from waveguide to microstrip with 50 ohm strip line. I used FR-4 as material and copper , rectangular waveguide as alumnium.

I got error whenever i try to simulate. I want to know how i will see S-parameters.

Moreover, when i design rectangular waveguide structure you will see the part of microstrip inside rectangular waveguide divided into two part and i have to define two times wave port 32 & 36. this i feel is not correct.
i am new user can anyone explain or download my comsol file , make it correct and send me.

I will be thankfull to you

I have attached the comsol file and also one image file to show what i want to design.

best regards,
Mehdi Khan