I'm getting error in deep convolution neural networks

Sir, I'm getting error by using the above code.

filename=['D:\MATLAB\R2017a\bin\Deep Learning\imgs'];
imds = imageDatastore(filename,...
    'IncludeSubfolders',true,...
    'LabelSource','foldernames');
imds.ReadFcn = @(filename)readAndPreprocessImage(filename);

[imdsTrain,imdsTest] = splitEachLabel(imds,0.7,'randomized');
numTrainImages = numel(imdsTrain.Labels);
net = alexnet;
net.Layers

inputSize = net.Layers(1).InputSize
%augimdsTrain = augmentedImageDatastore(inputSize(1:2),imdsTrain);
%TaugimdsTest = augmentedImageDatastore(inputSize(1:2),imdsTest);
label=classify(net,imdsTest)
function Iout = readAndPreprocessImage(filename)

I = imread(filename);

% Some images may be grayscale. Replicate the image 3 times to
% create an RGB image.
if ismatrix(I)
    I = cat(3,I,I,I);
end

% Resize the image as required for the CNN.
Iout = imresize(I, [227 227]);

end

My error is Struct contents reference from a non-struct array object. Please resolve the issue as early as possible.