Hello comunity

I work with to cursor where i keep information of my documento (header invoice) and Linhas (Lines of invoice).

I try to use this code:
LOCAL loXMLAdapter AS XMLAdapter


Select ft.ftstamp,fdata, fno,no, nome, morada,local,codpost from ft order by ft.fno into cursor Documento where ft.fno = 121005551

Select fi.ftstamp, fno,ref,design,qtt, epv,etiliquido,usr4 AS 'Codpautal',codigo from fi order by fi.fno into cursor Linhas where fi.fno = 121005551


SELECT Documento
SET RELATION TO ftstamp INTO Linhas ADDITIVE


loXMLAdapter = CREATEOBJECT([XMLAdapter])


WITH loXMLAdapter AS XMLAdapter
.XMLSchemaLocation = [AddTableToSchema_Nest.xsd]
.RespectNesting = .T.
.AddTableSchema([Categories])
.AddTableSchema([Products])
.ToXML([AddTableToSchema_Nest.xml], [], .T.)
MODIFY FILE AddTableToSchema_Nest.xml
ENDWITH

loXMLAdapter = .NULL.

But, this script return this error:
Code 26
Line: 10
Message 1: Table has no index order set.

someone could give me some help

Best regards,

Luis Santos