MarketPress Manage Orders page error

Hi!

Love the marketpress plugin but I just noticed that on the Manage Orders page I am getting the following error:

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'marketpress-orders' was given in /home2/mommycon/public_html/wp-includes/plugin.php on line 395

Not too sure where to start to fix this. I am using WP 3.1 and Marletpress 1.1.8

Any help you could give me is much appreciated thanks!