diff --git a/doc/form.md b/doc/form.md
index 13845031c..0150ad431 100644
--- a/doc/form.md
+++ b/doc/form.md
@@ -24,11 +24,22 @@ In here you can add elements to your form, add validations and filters of your
 choice. The creation method is invoked lazy just before a form is rendered or
 *isValid()* is called.
 
+In order to let icingaweb create a submit button for you (which is required for using the *isSubmittedAndValid*
+method) you have to call the *setSubmitLabel($label)* method, which will add a
+Zend_Form_Element_Submit element to your form.
+
 #### Calling is *isSubmittedAndValid()*
 
 *isSubmittedAndValid()* is used to check whether the form is ready to be processed or not.
 It ensures that the current request method is POST, that the form was manually submitted
-and that the data provided in the request is valid and gets repopulated in case its invalid.
+and that the data provided in the request is valid and gets repopulated in case its invalid. This only works when
+the sumbit button has been added with the *setSubmitLabel($label)* function, otherwise a form is always considered to be
+submitted when a POST request is received.
+
+If the form has been updated, but not submitted (for example, because the a button has been pressed that adds or removes
+some fields in the form) the form is repopulated but not validated at this time. is SubmittedAndValid() returns false
+in this case, but no errors are added to the created form.
+
 
 #### Pre validation
 
diff --git a/library/Icinga/Web/Form.php b/library/Icinga/Web/Form.php
index 797f749da..29b1ced8b 100644
--- a/library/Icinga/Web/Form.php
+++ b/library/Icinga/Web/Form.php
@@ -294,13 +294,14 @@ abstract class Form extends Zend_Form
         }
 
         if ($submitted) {
+            // perform full validation if submitted
             $this->preValidation($checkData);
             return $this->isValid($checkData);
         } else {
+            // only populate if not submitted
             $this->populate($checkData);
             return false;
         }
-
     }
 
     /**
diff --git a/modules/monitoring/test/php/application/forms/Command/DelayNotificationFormTest.php b/modules/monitoring/test/php/application/forms/Command/DelayNotificationFormTest.php
index 3e8536b2f..6c04d8f1c 100644
--- a/modules/monitoring/test/php/application/forms/Command/DelayNotificationFormTest.php
+++ b/modules/monitoring/test/php/application/forms/Command/DelayNotificationFormTest.php
@@ -39,7 +39,8 @@ class DelayNotificationFormFormTest extends BaseFormTest
     public function testInvalidMinuteValue()
     {
         $form = $this->getRequestForm(array(
-            'minutes' => 'SCHAHH-LAHH-LAHH'
+            'minutes' => 'SCHAHH-LAHH-LAHH',
+            'btn_submit' => 'foo'
         ), 'Monitoring\Form\Command\DelayNotificationForm');
 
         $form->buildForm();
@@ -50,6 +51,7 @@ class DelayNotificationFormFormTest extends BaseFormTest
         );
 
         $errors = $form->getErrors('minutes');
+        $this->assertCount(1, $errors, "Asserting an error to be added when the minutes value is invalid");
         $this->assertEquals('notBetween', $errors[0], "Assert correct error message");
     }
 }