Oracle Reports 10g to 11g migration issue
I've seen this behaviour before when upgrading from 9i to 10g and when converting from Windows to Linux. The thing to do is open the 10g-windows-created file in the 11g-linux editor, put everything in its right place and then save the file. It should render correctly after that.
It's unfortunate as it's a labour-intensive solution. I'm not sure if this is a bug or if .rdf files aren't intended to be platform- and version-independent.