Error using CR XI to consume a XML web service datasource

[hb2]

I'm trying to consume a web service using the XML datasource. I can see the various tables and fields in CR designer, but when I try to retreive data I get the following errors:-

'Failed to retrieve data from the database.'

'cannot determine the queries necessary to get data for this report. details: unexpected error'

Any ideas?

thanks in advance

hb2