class AddEmail_Controller extends Page_Controller {
private static $allowed_actions = array(
'AddEmail'
);

public function AddEmail() {
$form = new Form(
$this, // controller
"AddEmail", // form name
new FieldList( // fields
TextField::create("AgentName"),
TextField::create("Address"),
EmailField::create("Email"),
TextField::create("Company"),
NumericField::create("Phone"),
DropdownField::create("Dropdown",
"Location",
array(
'Sydney',
'Canbera',
'Perth',
'Melbourne',
'Malaysia',
'HongKong'
)),
DropdownField::create("Dropdown2",
"Location",
array(
'Australia',
'China',
'Malaysia',
'HongKong'
))),
new FieldList( // actions
new FormAction('doAddEmail', 'ubmit')
)

);

return $form->renderWith('AddEmailForm');

}
public function doAddEmail($data, $form) {
return $this->redirectBack();
}

}

When I click the submit button, it doesn't redirect back to the form as its supposed to do.

What does it to instead?

It is supposed to go back to the original form. But it returns a incomplete form page unlike the original somewhat change the URI.

Can you post a screenshot of what the incomplete result looks like?

"return $form->renderWith('AddEmailForm');" should be "return $form" - you need to return the actual form object.

And to further what ajshort said, if you want to provide a custom template use $form->setTemplate() in that case.

I did what you say and here is the screenshot

This error message is the CSRF_FAILED_MESSAGE warning. If you have a custom form template make sure it contains the SecurityID field, or if the form is non destructive you can disable the CSRF token by calling $form->disableSecurityToken()