The foloowing code generates an error; what's wrong with the code?
Invalid Index. (Exception from HRESULT:0x800200B (DISP_E_BADINDEX)


dim sSortBy as string = "MySortField"
Dim FieldDef As FieldDefinition
FieldDef = crDoc.Database.Tables(0).Fields(sSortBy)
crDoc.DataDefinition.SortFields(0).Field = FieldDef
crDoc.DataDefinition.SortFields(0).SortDirection = 
CrystalDecisions.[Shared].SortDirection.DescendingOrder
ViewReport.CrViewer1.ReportSource = crDoc