Update Sales Order with XML

Hi Everyone

I'm trying to update a Sales Order using XML using DI API (B1 9.0 PL08) but am getting an error (Error: -1029) - [ORDR.EDocStatus][line: 1], 'Field cannot be updated (ODBC - 1029)'.

When updating the same Sales Order with basically the same XML through DI Server it works as expected.

Does anyone know how to update a marketing document using XML?

The code I'm using is:

oCompany.XmlExportType = BoXmlExportTypes.xet_ExportImportMode;

Documents doc = (Documents)oCompany.GetBusinessObject(BoObjectTypes.oOrders);

doc.Browser.ReadXml("SO.xml", 0);

int res = doc.Update();

The XML is:

<?xml version="1.0" encoding="utf-16"?>

<BOM>

  <BO>

    <AdmInfo>

      <Object>17</Object>

      <Version>2</Version>

    </AdmInfo>

    <QueryParams>

      <DocEntry>259</DocEntry>

    </QueryParams>

    <Documents>

      <row>

        <DocDate>20140728</DocDate>

        <DocDueDate>20140730</DocDueDate>

        <CardCode>C20000</CardCode>

        <DocEntry>259</DocEntry>

      </row>

    </Documents>

    <Document_Lines>

      <row>

        <ItemCode>A00001</ItemCode>

        <Quantity>2</Quantity>

        <LineNum>0</LineNum>

        <DocEntry>259</DocEntry>

      </row>

    </Document_Lines>

  </BO>

</BOM>

I've also tried with B1 8.82 PL08 and got the same error.

Any help will be greatly appreciated.

Regards

Edu