before with the old wallet, when I unlocked for staking I could see the little diamond icon on the bottom right turning into a blue icon, now it says "staking is not active" with the version 3.0.1.0, do we need to add some new setting in the conf file to allow staking ?
Hmm... You should still see the Diamond turn Blue after unlocking. Make sure you wait until it has sync'd and wait one more minute before unlocking. If that does not work, try going to Slack. There is a DMD channel specifically for Support.
And also if there are no mature coins (all staked in last 24hours) the diamond don't become blue, until some coin return from the staking lock.