If the specified field index is out of range, the GetFieldByArea method returns null (Nothing in Visual Basic). To obtain the number of fields in a particular area, use the pivot grid's DevExpress.XtraPivotGrid.IThreadSafeAccessible.GetFieldCountByArea method.
Note
Hidden fields cannot be addressed by the GetFieldByArea method.
To obtain a list of fields located in a specific area, use the GetFieldsByArea method.