I think there might be an error in the electrode positions given in the excell sheet on the Biosemi website. FOr instance Cz is 0, 0 (in azimut and latitude )and FCz (which is just anterior to Cz) has the values 23, 90. This is not possible (or am I wrong?). FCz should have values something like 0, 10.
Have you ever used these values at all? Or are you using another file to define the electrode positions?
Why is the value not possible ? Why should the values be 0,10 ? If you claim that there is an error, than please provide a justification for your claim.
The polar coordinates are given in degrees, and used successfully by hundreds of our customers.