Matlab Warning: This concatenation operation includes an empty array with an incorrect number of rows.

I tried to do a t - test on my data which is cortical thickness data from 42 subjects. When I typed in the command: slm = SurfStatT( slm, bms.B - bms.K ), I got this warning: Warning: This concatenation operation includes an empty array with an incorrect number of rows.

Concatenation including empty arrays will require all arrays to have the same number of rows in a future release.

> In SurfStatT at 44.

I went to look at the details of the warning and, this is what I found out:

[n,p]=size(slm.X);
contrast=double(contrast);
pinvX=pinv(slm.X);
if length(contrast)<=p
  c=[contrast zeros(1,p-length(contrast))]';
  if sum((null(slm.X)'*c).^2)/sum(c.^2)>eps
      error('Contrast is not estimable :-(');
      return
  end

I then tried to relaunch my model, and I got the same warning. As before I went to look at the details of the warning, and this is what I got.

else
  c=pinvX*contrast;
  r=contrast-slm.X*c;
  if sum(r(:).^2)/sum(contrast(:).^2)>eps
      warning('Contrast is not in the model :-(');

Does anybody have any idea how to fix this problem? I have checked my txt. - files and they all seem to be okay.