Error when mineBlock and sendTransaction

[21470669]

I followed the Readme and type below 2 commands but encountered error: curl -X POST http://localhost:3001/mineBlock curl -H "Content-type: application/json" --data '{"address": "04bfcab8722991ae774db48f934ca79cfb7dd991229153b9f732ba5334aafcd8e7266e47076996b55a14bf9913ee3145ce0cfc1372ada8ada74bd287450313534b", "amount" : 35}' http://localhost:3001/mineTransaction