Disable or lock page field
 

I have three page fields in my Pivot.
First Page Field - Countries has distinct values US , UK , JPN
etc)
Second page field - Employee Type has distinct values Permanent,
Temporary and Contractors
and third Field called Bonus has values Yes and No. I want to diable
the pagefield , called Bonus once I select country not equal to US.
How can I do it using VBA in Excel 2003
Any help on this?