Error using makeState (line 56) Your fitness function must return a scalar value.

Hello Matlab users I'm getting started with GA and trying to apply it to maximization problem I have. Running the Genetic Algorithm gives the following error:

Error using makeState (line 56) Your fitness function must return a scalar value. Error in galincon (line 17) state = makeState(GenomeLength,FitnessFcn,Iterate,output.problemtype,options);

Error in ga (line 359) [x,fval,exitFlag,output,population,scores] = galincon(FitnessFcn,nvars, ...

Error in GA (line 24) [x,fval,reason,output,population,scores]=ga(@MyCost,24,[],[],[],[],lb,up,[],option);

Error in galincon (line 17) state = makeState(GenomeLength,FitnessFcn,Iterate,output.problemtype,options);

Error in ga (line 359) [x,fval,exitFlag,output,population,scores] = galincon(FitnessFcn,nvars, ...

Error in GA (line 25) [x,fval,reason,output,population,scores]=ga(@MyCost,24,[],[],[],[],lb,up,[],option);

I attached my code,I would be grateful if you help me.

Thanks