I'm not quite sure what you're trying to do here. Are you trying to get items from a column in a SharePoint List or are you trying to access data held within an XML document that is in a SharePoint Form Library?
If you are trying to get information from a SharePoint list you can use the Data Connection wizard to get that rather easy, try this:
1. Choose Data Connections from the Tools menu.
2. Click Add.
3. Select Receive Data, and then click Next.
4. Select SharePoint Library or List, and then click Next.
5. Select your SharePoint List from the lists of choices, and then click next.
6. Select each of the columns that you would like to get information from, and then click Next.
7. Click OK.
If you are trying to get data held within a list inside of a document (which I think is what you are trying to do) you will have to promote this node to SharePoint when you publish the form. Then, after you have done this, you can follow the steps above (choosing the library instead of the list) and get the information.
To promote your fields to SharePoint, follow these steps:
1. Choose Publish from the File Menu, click Next.
2. Select SharePoint Form Library, and then click Next.
3. Select Create a new SharePoint Form Libarary, and then click Next.
4. Type the URL of your SharePoint site, and then click Next.
5. Type a name for your library, and then click Next.
6. Click the Add button to add nodes that you would like to make available as SharePoint column names.
7. Click Finish.
I hope this helps, if this wasn't quite what you were trying to accomplish, please provide a little more detail.
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Matt Faus
InfoPath Dev Texas
Matt Faus / Microsoft InfoPath MVPQdabra® Software / Streamline data gathering to turn process into knowledge