Issue with ClientScript.RegisterClientScriptBlock

I have an application that I need to call a new window to open up a report.  Here is my full line statement:  ClientScript.RegisterClientScriptBlock(Me.GetType, "newwindow", "<script language=javascript>window.open('" & QueryString & "', 'NewWindow')</script>")

The problem I'm having is the new screen doesn't open up.  It just runs through the code and stays on the same page with opening a new page for the report.  The other thing is that I have the same line of code in another application and it works correctly.  The only difference that I can find is that the application that doesn't work is using a tab control from AJAX.  Could this be my problem?  Thanks for the help.