in the admin/scripts/products_results.js file, change the following 2 lines:
29:
var thepage = "Update_ProductCoupons.php?Add=1&ProdID="+ProdID+"&GroupID="+GroupID;
33:
var thepage = "Update_ProductCoupons.php?ProdID="+ProdID+"&GroupID="+GroupID;
to:
29:
var thepage = "update_productcoupons.php?Add=1&ProdID="+ProdID+"&GroupID="+GroupID;
33:
var thepage = "update_productcoupons.php?ProdID="+ProdID+"&GroupID="+GroupID;