Error in parallel computing for optimization of parameters in a simulink model using genetic algorithm

I am trying to optimize 19 parameters of a simulink model of a hybrid electric vehicle using genetic algorithm. The code runs properly in serial computing mode. I want to use parallel computing to speed up the calculations. Please find attached the script files. The function objective_function_4 computes the fitness function value. This function calls the function eq_fuel_eco_calc to run the simulink model and calculate the equivalent fuel economy of the hybrid vehicle over the given drive cycle. I am using MATLAB R2015b. The options in ga are set to 'UseParallel'=true and 'Vectorize'='off'. The fitness function of the first individual of the population evaluated correctly without any error. But after that, this is the error message that I received:

Error using objective_function_3 (line 12)
Struct contents reference from a non-struct array object.

Error in createAnonymousFcn>@(x)fcn(x,FcnArgs{:}) (line 11)
fcn_handle = @(x) fcn(x,FcnArgs{:});

Error in fcnvectorizer (line 16)
        parfor (i = 1:popSize)

Error in makeState (line 58)
        Score =
        fcnvectorizer(state.Population(initScoreProvided+2:end,:),FitnessFcn,1,options.SerialUserFcn);

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_optimization_4 (line 87)
[x,fval] = ga(FitnessFcn,nvars,A,B,Aeq,Beq,LB,UB,[],[],options);

Caused by:
    Failure in user-supplied fitness function evaluation. GA cannot continue.

Please help me in resolving this error. How does ga evaluate the fitness of population in parallel computing? Thank you!

[Rakesh Kumar]

Can you run this code by removing GA from the equation?

fval = zeros(10,1);
parfor ii = 1:10
   X = LB + (UB-LB).*rand(1,numel(LB))
   fval(ii) = FitnessFcn(X);
end