Error when using optimtool for genetic algorithm

My fitness function file is:

function y=asdf(x)

y(1)=(1000000+2000000+1500000+300000+500000+350000+3*x(1)+4*x(1)*0.6+3*x(1)*0.6*0.3+8*x(2)+40*x(3)+4*x(1)*0.6*0.2+4*x(1)*0.6*0.3*0.35+2*x(2)*0.15+80*x(4)+15*x(1)+8*200*x(1)+8*150*x(2)+3*150*x(5)+8*100*(x(3)+x(6))+8*50*(x(7)+x(8))+20*(x(3)+x(6)-x(7)-x(8))+60*(10000-x(7)-x(6)+500-x(8)));

end

There are 8 number of variables.

When I run the code, it says:

"Optimization running.

Error running optimization.

Too many output arguments."

How do I solve this problem?

[Stephan]

please provide your full code.