redirect not working

[eluser]seonghuhn[/eluser]
I'm a newbie to CodeIgnitor and I'm afraid this question might be a little naive. Nevertheless...

I have a form which correctly calls my email function in my controller which is called Coupon.

At the end of this function I want to redirect back to the index page. But it never does though I tried:

redirect('coupon');

redirect('coupon/');

redirect('coupon/index');

redirect('coupon/index/');

redirect('/');

As added information coupon is configured as my default controller in routes.php.

I am pretty confused since my application so far is very simple and is basically a copy of the video tutorial.

Your help would be most appreciated. :-)

Thanks,
Frank