Optimisation in Ansoft Designer

Hi,
I have a question. I was trying to use the Optimetrics on the patch antenna design. I created local variables for things I want to change in parametric solution. Default values are set for the original design, but in the parametric solution I changed the starting values ("override" box and putting new values). Everything in paramatric setup I set not to make any colisions between vias which I move (shorting pins and probe feed), but when I start the parametric analysis Designer seems to remember default values of the project saying that vias are overlapping when one of the shorting pins is near the default feed position. In the same time feed, by local variable, is set to be in another position, when doing analysis. It seems strange for me, but maybe someone has got the solution. Maybe instead of local variable use "parameter". BTW.. Can someone explain me what is the difference between "local variable" and "parameter default"?

Thanks in advance,
Redi.