AD7616 Diagnostics

The calculated Vcc and LDO code results from the transfer functions are diifference from Figure66 and Figure67.
ex. Vref=2.5V ,Vcc=5V : Vcc code= ((4xVcc)-Vref)x32768/(5xVref)=((4x5)-2.5)x32768/(5x2.5)=45875.2
Figure66 Vcc=5V : Expected output is around 25500.
What is differece of these results?