title: Compare validation for two custom control
body: <p>I have scenario, Page contains Check in date and Check out date for input. I used user control for datepicker, so both dates are called same user control. 
  Like,</p>
  
  <p>Check In Date: <code>&lt;uc:datepicker ID="CheckInDate" runat="server" /&gt;</code>
   Check Out Date: <code>&lt;uc:datepicker ID="CheckOutDate" runat="server" /&gt;</code></p>
  
  <p>Now I do validation for both dates which should not be blank like.</p>
  
  <pre><code>public class CustomiseDatePickerValidator : BaseValidator
   {
  
     protected override bool EvaluateIsValid()
          {
              Control c = this.FindControl(this.ControlToValidate);
              DatePicker datepickerSelected = c as DatePicker;
              ICustomiseRadDatePicker additionUserControl =    (ICustomiseRadDatePicker)c.Parent;
  
              if (string.IsNullOrEmpty(datepickerSelected.DateInput.Text))
               {
                  return false;
               }
  
              return true;
          }
   }
  </code></pre>
  
  <p>This is working fine but I want also compare both datepicker value So Check in date Should be less than Check out date</p>