I myself have repeatedly tried to load files onto google co-op. This is what I get back:
Log: XML parsing errors:
Wrong toplevel element-- should be Results
Line: 3
I have tried every way that I know to get past this. My XML editor say that it is valid.
  

Can you upload the XML somewhere and post a link from here?

I think this is the same issue all the Co-Op folks had.. the sample XML had some syntax errors . If tis stickly followed, then a parse /ipload err occurs