501 Confirmation Page Error

I am receiving this error on the confirmation page of this plugin. I read of few previous threads but not sure how to fix. Any information you can provide to assist would be appreciated.

Thanks in advance

Warning: sprintf() [function.sprintf]: Too few arguments in /home/content/85/7901885/html/wp-content/plugins/marketpress/marketpress-includes/plugins-gateway/paypal-express.php on line 501
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