asp.net Button OnClick event not firing

Because your button is in control it could be that there is a validation from another control that don't allow the button to submit. The result in my case was to add CausesValidation property to the button:

<asp:Button ID="btn_QuaSave" runat="server" Text="SAVE" OnClick="btn_QuaSave_Click" CausesValidation="False"/> 

Have you copied this method from other page/application ? if yes then it will not work, So you need to delete the event and event name assigned to the button then go to design and go to button even properties go to onClick event double click next to it, it will generate event and it automatically assigns event name to the button. this should work