4-way mixed-model ANOVA using anovan?

I am trying to run a 4-way ANOVA (2x2x2x2) with 1 between-subject factor and 3 within-subject factors. I am using the anovan function from the statistics toolbox as described here: http://www.mathworks.com/matlabcentral/newsreader/view_thread/58226 It worked perfectly for a 3-way ANOVA, giving me exactly the same results as SPSS but after adding another within-subject factor it calculates wrong F- and p-values. The sum of squares are identical to the SPSS output, so my input is correct.

Does anyone have an idea how to solve this problem? Or is there another possibility to run an N-way mixed-model ANOVA in MATLAB?