protected void cvLateralId_ServerValidate(object source, ServerValidateEventArgs args) { FullLengthLiningLateralDetails model = new FullLengthLiningLateralDetails(fullLengthLiningTDS); // Initialize CustomValidator cvLateralId = (CustomValidator)source; args.IsValid = true; // Verify in this step if (model.ExistsByLateralId(args.Value)) { cvLateralId.Text = "Duplicated lateral. (you already have this lateral here)"; args.IsValid = false; } }