Simplified Field Notation: Calculation field not updating in real-time

Hi everyone,
 
I'm new to forms and I'm trying to perform some very simple calculations on a sales/commission invoice...
I'm using Acrobat 9.
 
I have the following Fields (all in Number Format), all which are to be input by the user.
 
SalePrice
CommissionPercentage |This is numerical, 2 decimal places instead of Percentage format.
GrossCommission | SalePrice * CommissionPercentage
ConjunctionalPercentage |This is numerical, 2 decimal places instead of Percentage format.
ConjunctionalFee | SalePrice * ConjunctionalPercentage
NetCommission | GrossCommission - ConjunctionalFee
 
I'm entering the calculations in the 'Simplified Field Notation' area of the relevant field.
 
If I don't adjust the 'ConjunctionalPercentage', the the 'GrossCommission' and 'NetCommision' work fine, they update in real-time.
When I insert a figure into the 'ConjunctionalPercentage' field, the 'ConjunctionalFee' updates in real-time, however the 'NetCommission' doesn't.
The NetCommission field is one step behind, ie if I enter the 'ConjunctionalPercentage' as 1.0, nothing happens, but then if I enter 2.0 in the 'conjunctionalPercentage', the NetCommission is calculated based on the previous figure: 1.0.
 
If I update the 'ConjunctionalPercentage' figure by adding a 0 to the end, the calculation is correct, however this is not ideal.
 
Any help would be greatly appreciated.
 
Thank you.
 
~ PoeticKinetics.