Hear PAID_DATE as DATE
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataSourceID="SqlDataSource1">
<Columns>
<asp:BoundField ApplyFormatInEditMode="True" DataField="PAID_DATE"
HeaderText="DATE" SortExpression="PAID_DATE" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:STUDENTConnectionString %>"
SelectCommand="SELECT [PAID_DATE] FROM [MONTHLY_PAY_INFO]">
</asp:SqlDataSource>