diff --git a/grade/report/grader/edit_category_form.php b/grade/report/grader/edit_category_form.php
index 6ac37c8360e..70b5747327d 100644
--- a/grade/report/grader/edit_category_form.php
+++ b/grade/report/grader/edit_category_form.php
@@ -54,9 +54,15 @@ class edit_category_form extends moodleform {
 
             if ($grade_item->is_calculated()) {
                 // following elements are ignored when calculation formula used
-                $mform->removeElement('aggregation');
-                $mform->removeElement('keephigh');
-                $mform->removeElement('droplow');
+                if ($mform->elementExists('aggregation')) {
+                    $mform->removeElement('aggregation');
+                }
+                if ($mform->elementExists('keephigh')) {
+                    $mform->removeElement('keephigh');
+                }
+                if ($mform->elementExists('droplow')) {
+                    $mform->removeElement('droplow');
+                }
             }
         }
     }
diff --git a/grade/report/grader/edit_item_form.php b/grade/report/grader/edit_item_form.php
index 9670c61d659..32ff84910e1 100644
--- a/grade/report/grader/edit_item_form.php
+++ b/grade/report/grader/edit_item_form.php
@@ -42,32 +42,29 @@ class edit_item_form extends moodleform {
             }
         }
         $mform->addElement('select', 'scaleid', get_string('scale'), $options);
-        $mform->disabledIf('scaleid', 'gradetype', 'eq', GRADE_TYPE_TEXT);
-        $mform->disabledIf('scaleid', 'gradetype', 'eq', GRADE_TYPE_NONE);
-        $mform->disabledIf('scaleid', 'gradetype', 'eq', GRADE_TYPE_VALUE);
+        $mform->disabledIf('scaleid', 'gradetype', 'noteq', GRADE_TYPE_SCALE);
 
         $mform->addElement('text', 'grademax', get_string('grademax', 'grades'));
-        $mform->disabledIf('grademax', 'gradetype', 'eq', GRADE_TYPE_TEXT);
-        $mform->disabledIf('grademax', 'gradetype', 'eq', GRADE_TYPE_NONE);
-        $mform->disabledIf('grademax', 'gradetype', 'eq', GRADE_TYPE_SCALE);
+        $mform->disabledIf('grademax', 'gradetype', 'noteq', GRADE_TYPE_VALUE);
         $mform->setDefault('grademax', 100);
 
         $mform->addElement('text', 'grademin', get_string('grademin', 'grades'));
-        $mform->disabledIf('grademin', 'gradetype', 'eq', GRADE_TYPE_TEXT);
-        $mform->disabledIf('grademin', 'gradetype', 'eq', GRADE_TYPE_NONE);
-        $mform->disabledIf('grademin', 'gradetype', 'eq', GRADE_TYPE_SCALE);
+        $mform->disabledIf('grademin', 'gradetype', 'noteq', GRADE_TYPE_VALUE);
         $mform->setDefault('grademin', 0);
 
         $mform->addElement('text', 'gradepass', get_string('gradepass', 'grades'));
         $mform->disabledIf('gradepass', 'gradetype', 'eq', GRADE_TYPE_NONE);
+        $mform->disabledIf('gradepass', 'gradetype', 'eq', GRADE_TYPE_TEXT);
         $mform->setDefault('gradepass', 0);
 
         $mform->addElement('text', 'multfactor', get_string('multfactor', 'grades'));
         $mform->disabledIf('multfactor', 'gradetype', 'eq', GRADE_TYPE_NONE);
+        $mform->disabledIf('multfactor', 'gradetype', 'eq', GRADE_TYPE_TEXT);
         $mform->setDefault('multfactor', 1);
 
         $mform->addElement('text', 'plusfactor', get_string('plusfactor', 'grades'));
         $mform->disabledIf('plusfactor', 'gradetype', 'eq', GRADE_TYPE_NONE);
+        $mform->disabledIf('plusfactor', 'gradetype', 'eq', GRADE_TYPE_TEXT);
         $mform->setDefault('plusfactor', 0);
 
         $mform->addElement('advcheckbox', 'locked', get_string('locked', 'grades'));