additional images link in other language...

hi there i maby have a simple question for you guys but i can't seem to find the awnser.

in the main product page i need to change 2 names to my own country language first is : (product discription) and Additional images)

what i have done i have gone to the dutch.php language file and try to add it no luck page comes up white when i refresh.

when i go to the templates english.php i have found then

define('HEADING_TITLE_ADDITIONAL_IMAGES', 'Additional images');

and changed it to

define('HEADING_TITLE_ADDITIONAL_IMAGES', 'Meer Plaatjes');

and still no luck when i refresh my page it still shows additional images instead of 'Meer plaatjes'

how or where can i make changes for this :oops: