Retrieving value from INPUT element

I am trying to retrieve the value entered by the user from an INPUT element for a text box called "txtSearch" that is defined in the master page called Store.master I am trying to retrieve this through a function in code behind for a page called Listing.aspx When I run the application the value of "txtSearch" is always null even if a value is typed in the text box.
When you type a value in the text box does it have to be submitted or posted before it can be retrieved? Any help about resolving this would be greatly appreciated.
=============================== Store.Master =============================== <input type="text" style="width: 125px; padding-bottom: 5px;" id="txtSearch" name="search" runat="server"/> =============================== Listing.aspx.cs ============================== ...