Your code seems correct and is working fine on my end - I am attaching the page I used to test with as a reference and you can find a video I recorded here: http://screencast.com/t/WLIdolzgV
Please also note that the RadWindow's show() method does not take any arguments, as in my page.
Please also refer to your other thread, related to this matter: Ticket ID: 432721, 'Error: Unable to get value of the property 'GetWindowByName': object is null or undefined' for more tips on the possible origin of such an issue.
If you are still unable to resolve this please modify my page accordingly or post a list with the steps needed to reproduce it with my page so that we can give you a more relevant answer.
the Telerik team
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