Hi
I am not sure on the exact cause here, but as a check have a look at the XML file you are importing and see the node names actually included in the file, then compare that to the nodes specified in the XML port
As a first check make sure that every single node is in the file and port
A good way to test that is to export a record using the port and compare the layout to that of your import, the idea is to get it successfully importing before moving on to the next step
The next thing you can do is on the properties of the fields you can specify the min occurrences to 0, this will allow you to leave that field out of the port without an error
Hope this helps
Cheers
Nev