Why value from predicted value from the regression equation and predicted value directly from matlab are not matching?

I ploted the regression model using following codes (4 input P,V,T,H, and 1 output,TS)

X = [P, T, V, H, P.*T, P.*V, P.*H, T.*V, T.*H, V.*H, P.^2, T.^2, V.^2, H.^2];

Y = TS;

mdl = fitlm(X, Y);

disp(mdl);

coefficients = mdl.Coefficients.Estimate;

disp(coefficients);

yfit = predict(mdl,X)

I frormed the regression equation and calculated the predicted in excel, ideally it should match with the value I am getting from yfit = predict(mdl,X)

But it does not match. Can anyone explain why?

[Torsten]

How could we know the reason from the information you have given us ?