Coupons

Trying to create a coupon after recently upgrading my membership to "Pro". In the Add Coupon area, there is a fatal error: Fatal error: Cannot use string offset as an array in /home/content/s/t/e/{...}/html/{...}/wp-content/plugins/marketpress/marketpress.php on line 5607

Help? I launched a sale and am now going to have upset customers if they can't use the coupon.