I have tried to Solo mine two Neoscrypt coins with 13 different miners. 10 of them didn't start mining with the error "JSON-RPC call failed: Method not found", 3 of them gave the same error "reject reason: high hash" when the block was found.
So, at the moment I have checked everything: -f, -m, -i settings, various miners, ports, amount of cards, even tried to mine another Neoscrypt coin - every time the same error when I found the block.
If somebody can explain and fix this damn problem, I am ready to donate some coins...