thanks the problem is the x11 wallet does not support this command
I am thinking to use pure pos but how to make the wallet sync
Ok I'll save you from the ordeal of googling....
You need a cpuminer that can mine X11, like darkcoin-cpuminer.
Start two nodes, put server=1 into the conf of the one that's
going to receive the coins.
Then in a new terminal go to the dir where you have the miner and
./minerd -a X11 -o http://localhost:<rpcport > -u <rpcuser> -p <rpcpassword>
The stuff in the bracket comes from your conf file. Hope this helps..