question about the way data is imported

I'm trying to import data from 26 separate files into the variables u and v, and I want 26 separate instances each of u and v (ie u_1 through u_26). In the files, u and v are 29x39 doubles. I tried the following code to create u and v as 3D arrays:

 if true
    for k=1:26
    filename = sprintf('Angle1-%d.mat', k);
    data = load(filename);
    u = zeros(29, 39, 26);
    v = zeros(29, 39, 27);
    u(:, :, k) = data.u;
    v(:, :, k) = data.v;
  end

This made sense to me conceptually but it didn't seem to work in practice - the whole array ended up being zeros except for the last set of 29x39. Is there a better way to import this data?