Help with ravencoin mining

Looking for a little help mining ravencoin. I have NBMiner set up and i have my rigs pointed to mining with Nanopool and i set up my first rig and all went ok. Copied and pasted the start.bat file and ONLY changed the devices name. Now two out of four rigs are working correctly and one rig jsut gets a low difficulty error for both cards, and the other rig gets a low difficulty error for one of the cards. I cannot find anything on low difficulty errors other than for monero and thats not helpful really. Any help would be appreciated.