subdomain

hello
I am working on design of photonic crystal fiber with Comsol using RF(mode analysis). I am using comsol with MATLAB.
when I use loop in matlab to change the geometry to find the solution for each geometry,everything is ok but the subdomain is changed after some loops. Not all the subdomain are changed but just one subdomain is changed with anther subdomain
I do not know why this subdomain is changed.

please I need solution for this problem.

Thanks

Riyadh Moad