Question on centering partitions

[Scott Marshburn]

I was exploring different ways to center partitions to the mid stile I typed the following formula (replacing the text with the measurements) but the result is not correct has any one tried this method? If so could you give me some advice. I can use this formula in excel and it works fine I just thought it would be easer to do it in eCabinets
Frame opening width+(Stile width-Scribe-End Thickness)+(Mid Stile width/2)-(Partition Thickness/2)

[Scott Marshburn]

I made a Excel add in that will allow me to Calculate the openings needed to center the partitions on the mid stiles It allows me to work in eCabinets and with the form without having to toggle from one program to the next I can enter the data click calculate then click on the result and paste it into the opening width here is a video of it in action
http://screencast.com/t/76CixmSs