InfoPath Dev

I'm new to infopath 2007 but I'm devloping a a form that have a Main DS and a Secondary DS to a SharePoint List

The goal here is to have the user select a Firm (Firm_Name) and them populate the Account Id (Pfx_ID) problem I recieve an error from this code:

Public Sub Firm_Name_Changed(ByVal sender As Object, ByVal e As XmlEventArgs)

' Write your code here to change the main data source.

Dim XpathFirmName As String = "/my:myFields/my:Customer_Information/my:Firm_Name"

Dim strDataSource2 As String = "Project Information"

' Get a reference to the Project Information secondary data source,

' and create an XPathNavigator object for it.

' Create an XPathNavigator object positioned on the current site,

' which is the Select FirmName node in the main data source.

' Move to the parent of the SelectCustomer node, so that the code

' can access the FirmName node.

Dim selectedCustomer As String = XpathNavMain.SelectSingleNode(XpathFirmName, Me.NamespaceManager).ToString

Dim strQuery As String = "/dfs:myFields/dfs:dataFields/dfs:Project_Information[@Firm_Name='" & e.Site.InnerXml & "']/Pfx_ID"

Dim PFXid As string = XpathNav2.SelectSingleNode(strQuery, Me.NamespaceManager).InnerXML

My secondary problem is that there is actually a chance that a Firm will have 2 entries in the Project_Information datasource. In which case I need to populate a Second Dropdown list for them to select "/Project_Id" then finally populate a textbox with the creation_date.  

sorry the error I'm getting is "dsf namespace not defined"

 Hi,

 correct me if i'm wrong (never used 2007) but i thinkyou need to define the namespace before you can start working with it

Infopath 2003 code 

 var websobj=XDocument.DataObjects["list_machines"] ;     //list_machines is the name of my secondary data service

websDOM=websobj.DOM

websDOM.setProperty("SelectionNamespaces",'xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:dfs="http://schemas.microsoft.com/office/infopath/2003/dataFormSolution" xmlns:ns2="http://tempuri.org/"');

Dim XpathNav2 As XPathNavigator = Me.DataSources(strDataSource2).CreateNavigator

here you specify your secondayr datasource but you don't tell infopath what namespace to use, hence the dfs (dataformsolution) error i think