--- views_handler_filter_in_operator.inc	2011-07-21 13:31:25.000000000 +0800
+++ views_handler_filter_in_operator_new.inc	2011-07-21 13:34:20.000000000 +0800
@@ -357,6 +357,11 @@
   function validate() {
     $this->get_value_options();
     $errors = array();
+    
+    // Validate operator that doesn't require a value, if okay don't proceed with rest of validation.    
+    if (in_array($this->operator, $this->operator_values(0))) {
+      return $errors;
+    }    
     if (!in_array($this->operator, $this->operator_values(1))) {
       $errors[] = t('The operator is invalid.');
     }