optimizing neural network with NSGA-II

hello

I have a neural network structure of my data and I want to do a multiobjective optimization for example with NSGA-II. How could I connect my ANN to NSGA-II?

I tried the next code:

[x_ga1,fval_ga1,~,gaoutput1] = gamultiobj(fun,nvar,A,b,Aeq,beq,lb,ub,opts_ga);

where "fun" is my ANN function. but It makes an error!!