[SOLVED] Update posted transaction using SageDataObject220

I am trying to update a field inside a posted transaction.

This is what I have:

    Dim oWS As SageDataObject220.WorkSpace
    Dim SD As SageDataObject220.SplitData = oWS.CreateObject("SPLITDATA")
    SD.Open(SageDataObject220.OpenMode.sdoWrite)

    SD.FindFirst("TRAN_NUMBER", CInt("575031"))
    SD.Read(SD.RecordNumber())
    SD.Fields.Item("Details").Value = "575031 test"
    SD.Write(SD.RecordNumber())
    oWS.Disconnect()

I can locate the transaction, but trying to update the Details value does not work. It appears to be read only and only comparable.

Any suggestions?