Compiler Error Message: CS1061

Dear all,
Hello, im still developing some website project using ASP.net and im facing some error message after i compile its. The message is:
 
'ASP.resultspage_aspx' does not contain a definition for 'GridView1_SelectedIndexChanged' and no extension method 'GridView1_SelectedIndexChanged' accepting a first argument of type 'ASP.resultspage_aspx' could be found (are you missing a using directive or an assembly reference?)
Error Source:
Line 25:             SelectCommand="SELECT [home_id], [home_location], [home_type], [home_picture], [home_address] FROM [HomeTable]">
Line 26:         </asp:SqlDataSource>
Line 27:         <asp:GridView ID="GridView1" runat="server" AutoG ...