[Simulink Design Optimization] The cost function of suspension parameters.

I am analysing a suspension system to find optimized Ks and Cs(Orange ones in model). This is my model in Simulink:

Some errorrs occured in the cost funtion I put below.

function BAcost = CostF(data)
% CostFunction to compute BA with different Cs & Ks.

V = data.Nominal.BVelocity;
A = diff(V.Data)./diff(V.Time);
BAcost = max(abs(A));
end

Eorrors are shown as this.

The final line means that This type of variable does not support indexing using points.

The Input signal in the left of the Green box is a 40001*2 matrix of Gauss White Noise which contains time and power.

I write this code with reference to this cost function found in mathworks website.(this site)

I don not kown what's wrong with it.Hope you can help me.

If necessary, I will upload this model.