shift problem

I have designed RF PA in ADS 2008 version. i made three different design for 1.8425 Ghz frequency. but after making PCB, i have observed shift of 50 MHz in all three designs.
What could cause such problem, is it due to ADS ?
Plz help me, i can't able to locate cause problem.

Regards,

models lie.

do you calculate the Rin and Rout correctly, it seem have problem with the RLC circuit...
other root cause you can try check the SNR and reduce any unwanted noise..

did you consider the parasitic of the PCB in your ADS design simulation?