Next Gen Gallery returning error

Hi all,

Just checked my site and at the top of the page i am getting the error message:

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, ‘nggLoader::load_styles’ was given in /home/www/paulsmyth-photography.co.uk/wp-includes/plugin.php on line 395

can anyone shed any light on how I can fix this? I really need this plugin to be working so all suggestions welcomed.

Thanks in advance

Kyle