Problem about ADS momentum

Hello everyone!
I have some trouble in simulation of microstrip structure under ADS Momentum environment. I defined all the strip in the circuit as sheet originally and got a conclution. Now I rebuild all of them as thick metal using the momentum's auto thickness expansion funtion with all shapes same, then I got a conclution far deviate from the former one, which confused me so much. Further more I found all the microstrip simulated with thick metal defined exhibit a inductance lower obviously than simulated with sheet defined.
I'm new to em simulation tools, and I have no ideal about why this happened, what should I do?

What is the thickness of the sheet or layer and what freq are u operating, also the substrate.

When you are using a thick conductor option, be careful that thickness of the strip is now added to the thickness of dielectric as well. therefore your substrate thickness has changed. you have to take a look at the substrate definition document from ADS.