InfoPath Dev

I'm trying to populate a field with data that is in columns available from a secondary source coming from SharePoint. DataSource has 3 columns: ID, Cost_Code & Title. Dropdown shows Cost Code and text box should display Title. Using a rule to set the fields value with the following xpath expression:
xdXDocument:GetDOM("Cost Code")/dfs:myFields/dfs:dataFields/dfs:Cost_Code/@Cost_Code[ID = current()]
Could someone please tell me what I am doing wrong?

Could you provide a tree of your data source? I think it looks like this:

Cost_Code
--Cost_Code
--ID
--Title

And if so, you're XPath should be this:

xdXDocument:GetDOM("Cost Code")/dfs:myFields/dfs:dataFields/dfs:Cost_Code/@Cost_Code[../@ID = current()]

Matt, your guess is correct. I've copied you xpath statement without any success. How can I provide a tree of my data source?
Dean

What guess was correct? To provide a tree, you can just do it in text kind of like I did it above.

Also - your drop-down list uses the ID field as the "value" right? Make sure that your display name is "Title".