This sets the field BO2 to zero if BO1 is zero,
IIF( IIf(IsNull([BOI]),0,[BOI])=0,0,[BO2] )
This sets the field BO3 to zero if BO2 is zero and BO2 to zero if BO1 is zero,
IIF( IIF( IIf(IsNull([BOI]),0,[BOI])=0,0,[BO2] )=0,0,[BO3] )
The " in the code my set the filed to a string so check if...