AddDataField if the field exists?

[theta]

I am producing a pivot table through VBA. Everything works fine. The XML files I am now using have changed slightly - some contain an extra field called 'NetSum'

I would like to include another line in the VBA so that if 'NetSum' exists, then it should be included in the pivot. Basically need an IF statement for the below ?

    oPT.AddDataField field:=oPT.PivotFields("NetSum"), Function:=xlSum

Any help appreciated

Regards

L