FEM error

Hello every one.
i am new to this COMSOL and with the help some tutorial i learned how to use. i am much familiour with Matlab.
i want to ask 1 question, which i am facing in my most of the models.
let me excplain you how i make model and use. may be i am doing some mistake there.
1) i made my model in MATLAB using COMSOL functions .
2) Then i load it COMSOL using file -> import -> Geometry objects. assign sub domain and boundary conditions. choose solver if required and save the model in (.m) MATLAB file.
using this Matlab code i assign different conductivity and permitivity with other same boundary conditions.

till here its working fine,

now when i made one big cylinder C1 with the radius of 0.5 cm and cylinder C2 with the radius of 0.05 cm. apply step (2).
now in the MATLAB code if i change the radius of C2 0.1 cm i gives me error

??? Error using ==> fem2jxfem at 60
Errors found in FEM structure.

Error in ==> multiphysics at 81
jxfem=fem2jxfem(fem,femname(inputname(1),fem),{'lib'},false,false);

i checked the no of boundary, subdomain are same for both cases.
can anyone help me how to solve this error