query string in hyperlink

hi,
In my master page am using hyperlink to navigate to the other child page.
here i use querystring in the hyperlink ie;
<asp:Hyperlink id="hyp" runat="server" NavigationUrl="Default.aspx?value='<%# dropdownlist.SelectedValue%>'"/>
but this above line is not working.Please help out to know  where i have gone wrong in the code.
thank you.
 
 
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