It didn't work, I have my wallet encrypted, could be a factor?
I type
"setgenerate true 200"
in the debug window and doesn't give me any error, but if I type "getinfo" it always says
"staking status" : "Staking Not Active",
I took an old copy of the "blocks" directory (that I know is fine, I stacked more than one months after the last time I had to do it) but not joy either
if the number of the last block in your wallet matches the number on this site -
https://chainz.cryptoid.info/dmd/#lock wallet and unlock it again after 2 minute for POS staking mode.
All the steps to start working with the wallet are described here - 8. Q:
https://diamond-info.github.io/#q8