InfoPath Dev

Data from my secondary data source is returned in a diffgram (repeating table). I need to clone the diffgram data so that I can store the data in another repeating table in the main data source. Whenever I try to add (appendChild) the cloned row to the repeating table in the main data source, I get an error that it is the wrong type. What am I doing wrong?

What is the namespace(prefix) that you are using for your secondary datasource? Is it the same as main datasource?
If not you cannot just append the node from secondary datasource to main datasource.

To get it to work, you need to create the nodes of Main datasource type and set the values to that node and append this node to the main datasource repeating table.