hfss 11 stripline

Hi all,
I'm a freshman in HFSS and also in electromagnetic simulation concept. So, I'm not so sure about whether i'm correctly simulating or not. Here is my problem:

I have a stripline structure with a splitted upper reference plane. I want to simulate in HFSS this structure and also the same structure with no splitted plane and want to compare the port impedances to see the effect of the split.
But their individual simulations results gave me the same port impedances and i'm confused at this point.

I'm posting you my files, anyone can give a look at this files are mostly welcomed.

Best regards,