showModalDialog close from server side after processing

Hi 
This is the first thread I am writing in ASP.NET community forum and I know that somebody is going to give me the solution in which I have been stuck for the past one week or so.
The issue is that I have used window.showModalDialog to opened a dialog and after processing I need to close it but somehow it is not closing. 
To resolve that I did some google and found the solution but that solution is not working on my end.
a) ScriptManager.RegisterStartupScript(this, GetType(), "closePage", "<script language='javascript'>window.close();</script>", true);
b) ClientScript.RegisterStartupScript(typeof(System.Web.UI.Page), "closePage", "<script type='text/JavaScript'>window.close();</script>");
I have written this line of code after calling Save() method but it throws me javascript syntax error window
kindly provide me some solution 
Thanks
Bilal



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