How do I make a postback when date is selected from calendar

Question

Dear,

I have a grid with date column where i want to make a postback or trigger an textbox event when user selects date from calendar inside a gridview with edit mode.

but the below code does not trigger text box changed event..

I want to trigger a textbox/calendar event when user makes a selection.

 

I have tried

 

 

<asp:TemplateField HeaderText="Date" > <itemtemplate>

<asp:TextBox ID="txtDischargeDate" runat="server" ReadOnly="true" CssClass="txtb" Width="80px" OnTextChanged="txtDischargeDate_TextChanged">

<asp:Image ID="Image2" runat="server" ImageUrl="~/Images/ew_calendar.gif" />

<cc1:calendarextender cssclass="cal_Theme1" id="Cal1" runat="server" popupbuttonid="Image2" targetcontrolid="txtDischargeDate">