I don't really get your problem but from the error message, there may be a naming conflict.
Suggestions
- You can try to do some renaming
- You carefully check the type of ListPrice you're trying to access (it is possible you're mistaking the ListPrice Node in the XML for ListPrice Column in Table.
- Set a Breakpoint to see what went wrong at that point.
Note: The above are suggestions as your question is not clear to me