i have an error in implementation dropout code

function [W1, W2, W3, W4] = DeepDropout2(W1, W2, W3, W4, X, D)

alpha = 0.01;

N = 5;

for k = 1:N

x = reshape(X(:, :, k), 25, 1);

v1 = W1*x;

y1 = Sigmoid(v1);

y1 = y1 .* Dropout(y1, 0.2);

v2 = W2*y1;

y2 = Sigmoid(v2);

y2 = y2 .* Dropout(y2, 0.2);

v3 = W3*y2;

y3 = Sigmoid(v3);

y3 = y3 .* Dropout(y3, 0.2);

v = W4*y3;

y = Softmax(v);

d = D(k, :)';

e = d - y;

delta = e;

e3 = W4'*delta;

delta3 = y3.*(1-y3).*e3;

e2 = W3'*delta3;

delta2 = y2.*(1-y2).*e2;

e1 = W2'*delta2;

delta1 = y1.*(1-y1).*e1;

dW4 = alpha*delta*y3';

W4 = W4 + dW4;

dW3 = alpha*delta3*y2';

W3 = W3 + dW3;

dW2 = alpha*delta2*y1';

W2 = W2 + dW2;

dW1 = alpha*delta1*x';

W1 = W1 + dW1;

end

end

i get this code from MATLAB Deep Learning With Machine Learning, Neural Networks and Artificial Intelligence — Phil Kim ebook

when try trianing network see this error:

Error using *

Inner matrix dimensions must agree.

Error in DeepDropout2 (line 9)

v2 = W2*y1;

Error in TrainingNetwork (line 46)

[w1 ,w2 ,w3 ,w4 ]= DeepDropout2(w1,w2,w3,w4,input_Image,correct_Output);