xml parsing error content is not allowed in prolog

[lightsailpro]

I am trying to set up a WebTrend REST API XML format using the xml file - remote url connector. I got  "xml parsing error content is not allowed in prolog" after I type in url, username, password and click Ok. Could anyone help? By the way I am using teiid 8.7 with designer 8.5 aplpha2 on Windows 7. Thanks

[shawkins]

Typically this would be seen when the XML is not valid, can you double check that accessing the url produces a valid doc?