Hello, Andy.
Thank you for using UltiDev Cassini. We'll do our best help you resolve the issue.
Although we have not tested web apps taking cross-domain services calls,
it seems that placing the ClientAccessPolicy.xml file into the same folder as your app's "physical location" folder should work. Please note that since all Cassini applications are at the "root" - because they have different port numbers but share the same host name, each of your silverlight apps hosted by Cassini is likely to need the ClientAccessPolicy.xml file in the same folder as the app's physical location.
Please let us know if this information has helped.
Best regards,
UltiDev Team.
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