How to access element in concatenated dataset and array?

Hi,

How to access element in an array which concatenate dataset and a cell array?

E(z) ok
E.labels(z) ok
E(z,3) NOT OK

A = dataset(trialA,trialAA);
....
for i = 1 : nvars
    B = horzcat(A(:,i), A.labels, cnums); %col2 actual class col3 predicted    
    C = B(:,1:3); % get each feature, its actual and predicted class
    [D I] = sort(C(:,1),'ascend'); % sort according to feature value
    E = C(I,:);
    .....
    for k=1:f
    .....
         for j = 1 : f
         .....
         for z = loc : m
         ......
         tf3 = isequal(E(z,3),lablist_pred(j));%test predicted class NOT OK
         ......
         tf4 = isequal(E.labels(z),k); %test actual class THIS LINE IS OK

Thank you

[per isakson]

Format please!