images classification with cnn error

clear all
clc
Path = 'D:\eegdata\*.jpg';
Files = dir(Path);  
for i=1:length(Files)
   fn = [Path(1:end-5) Files(i,1).name];
   I=imread(fn);
      I=imresize(I,[28,28]);
   I(:,:,3)=rgb2gray(I);
   [m,n,o]=size(I);
   if i<=30
trainD(:,:,:,1)= I(:,:,:);
   end
      if i>=31
trainD(:,:,:,2)=I(:,:,:);
      end
targetD=categorical([1;2]);
%% Define Network Architecture
% Define the convolutional neural network architecture.
layers = [
    imageInputLayer([m n o]) % 22X5X1 refers to number of features per sample
    convolution2dLayer(n,16,'Padding','same')
    reluLayer
    fullyConnectedLayer(384) % 384 refers to number of neurons in next FC hidden layer
    fullyConnectedLayer(384) % 384 refers to number of neurons in next FC hidden layer
    fullyConnectedLayer(2) % 6 refers to number of neurons in next output layer (number of output classes)
    softmaxLayer
    classificationLayer];
options = trainingOptions('sgdm',...
    'MaxEpochs',5000, ...
    'Plots','training-progress');
net = trainNetwork(trainD,targetD',layers,options);
predictedLabels = classify(net,trainD)'
end