Custom Validator and Compare Validator are Firing Same Time

Hello,
I am facing an issue which is i have Custom Validator on TextBox control and Compare Validator on the Same TextBox control now the issue is if custom validator and compare validator is firing at the same time.
My Scenario like this 
I am checking the Date in DD/MM/YYYY format in Custom Validator and the entered should not be greater than Todays date i am checking in Compare Validator so if my Custom Validator fails then it should not fire Compare Validator but its firing can any 1 please help me how can i Synchronize my above functionality.



<asp:TextBox ID="txtStartDate" runat="server" CssClass="TxtBox" Width="80px" Text=""/> ...