I hope You read Manual carefully. You have to use Private ACTIVE key for mining. Find it in two step at https://steemit.com/@youraccount/permissions:
- click box [login to show] - login
- click the box [show private key].
Copy&Paste. Should work now.
I really don't know what is for... and why so complicated.
Mining with slow latency internet connection is pointless.
I clicked on "login to show" and it wants me to login again, the username show my username/active, I use my master password and it says invalid password. I tried it without /active and master password, and it seemed to accept it but it does not show me my WIF. Help