unauthorizedacessexception is coming when writng file using asp.net

i want to write a aspx file using the editor control  and on the click of a button writing this code
and allowed read/write on the folder
this is the code
TextBox3.Text = Editor1.Content;
        string path =Server.MapPath(tag.Text);
        FileStream str = new FileStream(path+@"/"+name.Text+@".aspx",FileMode.Create);
        StreamWriter write = new StreamWriter(str);
        write.Write(Editor1.Content);
        write.Close();
        str.Close();
when cliking on the button i am getiing the error
unauthorizedacessexception

Access to the path 'c:\inetpub\wwwroot\WebSite\test1\c\play.aspx' is denied.please help
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