运行时出现登录按钮错误

Question

当我运行我的代码时，我在运行时遇到登录按钮错误..为什么我点击它时会得到一个简单的按钮应该验证但是对于那个设计我也会收到错误

ASP.userinterface_login_aspx' does not contain a definition for 'btnLogin_Click' and no extension method 'btnLogin_Click' accepting a first argument of type 'ASP.userinterface_login_aspx' could be found (are you missing a using directive or an assembly reference?)

这是我的设计

<asp:Button ID="LoginButton" runat="server" Text="Login" onclick="btnLogin_Click"   />