Index: branches/5.3.x/core/kernel/kbase.php
===================================================================
--- branches/5.3.x/core/kernel/kbase.php
+++ branches/5.3.x/core/kernel/kbase.php
@@ -529,7 +529,7 @@
 
 		$form_data = $config->getFormByName($this->formName);
 
-		if ( !$form_data ) {
+		if ( $form_data === false ) {
 			trigger_error('Form "<strong>' . $this->formName . '</strong>" isn\'t declared in "<strong>' . $this->Prefix . '</strong>" unit config.', E_USER_NOTICE);
 		}
 		else {