Index: library/Zend/Form.php
===================================================================
--- library/Zend/Form.php	(revision 22930)
+++ library/Zend/Form.php	(revision )
@@ -1782,6 +1782,10 @@
     {
         $group = array();
         foreach ($elements as $element) {
+            if($element instanceof Zend_Form_Element) {
+                $element = $element->getId();
+            }
+
             if (isset($this->_elements[$element])) {
                 $add = $this->getElement($element);
                 if (null !== $add) {
Index: tests/Zend/Form/FormTest.php
===================================================================
--- tests/Zend/Form/FormTest.php	(revision 22930)
+++ tests/Zend/Form/FormTest.php	(revision )
@@ -4388,7 +4388,16 @@
         $html = $form->render($this->getView());
         $this->assertEquals(1, substr_count($html, 'Customer Type'), $html);
     }
+
+    public function testAddElementToDisplayGroupByElementInstance()
+    {
+        $element = new Zend_Form_Element_Text('foo');
+
+        $this->form->addElement($element);
+        $this->form->addDisplayGroup(array($element), 'bar');
+        $this->assertNotNull($this->form->getDisplayGroup('bar')->getElement('foo'));
-}
+    }
+}
 
 class Zend_Form_FormTest_DisplayGroup extends Zend_Form_DisplayGroup
 {