xPath : url ... is invalid. why?

Hi,

I feed a url like the one below (fake example) into the module and I get an error that the message is invalid:

http://webservices.fakeAdress.com/websiteservices/EstateService.svc/GetE...{"ClientId":"152216705","PurposeIDList":[1],"CategoryIDList":[7],"Page":0,"RowsPerPage":500,"Language":"nl-BE","ShowDetails":0}is invalid.

When I paste this string into the browser it renders the XML like a charm. When the module cannot handle this kind of strings is there a known workarround?

Is there a way to save the XML to the server and import it on a given time?

thnx

sven