Trying to add LASER radiation source to a 3D model

Hello, i have a 3D model of the human eye, i'm trying to add a LASER source and to examine the heating distribution, i added materials for each domain such as absorption and scattering coefficients, heat capacity, mass density and conductivity as you can see here: for gaussian beam https://en.wikipedia.org/wiki/Gaussian_beam

under global parameters i added some parameters:

and some analytic expressions:

and i got this error:

what am i doing wrong?