Only fits rock river lefty lowers - Rock River Arms Left Handed RRAGE 2G .223/5.56mm Completed Upper

Ordered. Was waiting on the rest of my parts for my build. When it came time to assemble, the upper doesn't function properly. After doing some research, this upper only functions on a rock river lower that has the bolt release on the opposite side. Now i have this new upper sitting in a box and can't return it since I just passed the 30 day mark. No where in the description does it warn about this.