Set Message With strtolower('{field}') not working

I am trying to make the {field} display in lower case in set message but has first letter upper case.

PHP Code:

$this->form_validation->set_message('is_unique', 'This ' . strtolower('{field}') . ' all ready exists please choose another!'); 


There's only one rule - please don't tell anyone to go and read the manual.  Sometimes the manual just SUCKS!