How to plot error for multi-step ahead prediction using Narxnet..?

Hi,, all http://imageshack.us/photo/my-images/710/8yd9.png/ above link is the image result, predicted using narx net, now i'm trying to plot error, for those result , so i tried the below code, % Test the Network outputs = net(inputs,inputStates,layerStates); errors = gsubtract(targets,outputs); performance = perform(net,targets,outputs)

    % View the Network
    % view(net)

    % Plots
    % Uncomment these lines to enable various plots.
    %figure, plotperform(tr)
    %figure, plottrainstate(tr)
    %figure, plotregression(targets,outputs)
    %figure, plotresponse(targets,outputs)
    %figure, ploterrcorr(errors)
    %figure, plotinerrcorr(inputs,errors)

but it is showing error.. so would any one share a code for plotting error...?? please help...