RequiredFieldValidator runs even when CausesValidation is set to false. Esp when value has been assigned/bind to control being validated

Please refer to the code below. I use the code from this post. http://forums.asp.net/p/1396988/3182918.aspx#3182918 CausesValidation will work as expected only then no value has been assign/bind to the control in question. However when a value as been assigned,  RequiredFieldValidator will still run. This will be a grave concern if a ValidatorCalloutExtender is used. The ValidatorCallout will display and it will not disappear even though the CausesValidation is set to false.
1    <asp:DataGrid ID="DataGrid1" runat="server" DataSourceID="SqlDataSource1" AutoGenerateColumns="false" >
2            <Columns>
3            < Go to the complete details ...