Comsol with live link for Matlab

Hi All, I'm using the Comsol Multiphysics package with live link for Matlab. I need to rename and then to transfer the model calculated in a Matlab function to the main script and back again: I tried to send the model as a global variable and as a function argument, but in both cases I got that 'the object is no more in the model', please could someone help me? Thank you. Antonino