This message is displayed when you are trying to test a Silverlight Application on a computer where an unsupported version of Silverlight is installed. To test Silverlight applications with the functionality provided by the Silverlight Application Support plugin, TestComplete requires that Silverlight ver. 4.0.50826 or later be installed in the system. Only if such a version of Silverlight is installed on your computer, TestComplete can obtain the full access to internal objects, methods and properties of a Silverlight application that was properly prepared with the tcAgPatcher.exe command-line utility shipped along with TestComplete. Otherwise, if an earlier version of Silverlight is installed in the system, the Silverlight Application Support plugin cannot fully expose objects of the Silverlight application under test, and the TestComplete test engine cannot access such objects and their members.
You can get the latest version of Silverlight from Microsoft’s web site:
To learn more about testing Silverlight applications, see Testing Silverlight Applications.