Localization Problem?

I am really puzzled here, I have a plugin that is not for the life of me translating. The plugin was made by my self and I’ve seen it translate on many other installs (even on my own test ones) but not on a particular persons installation.

In the plugin I use this to load the textdomain

function automotive_load_textdomain() {
	load_plugin_textdomain('listings', false, basename( dirname( __FILE__ ) ) . '/languages/' );
}
add_action( 'plugins_loaded', 'automotive_load_textdomain', 99 );

And inside the /languages/ I have a file named “listings-nl_NL.po” and “listings-nl_NL.mo” (freshly generated files). Once I make a translation, upload the file and view the page it doesn’t work?

I checked and the person is using jetpack as well and it’s translated so it can’t be something with the installation can it?

Any help is appreciated,

Thanks, Dan.