coins minimum coin age is 2 hours while the maximum age is 30 days, basically staking takes place during that time, it already staked once but turned out as orphan, anyway don't worry as stated here..
I'm not worry, i just curious why my wallet are not staking even if i keep it open for few days while other PoS coins i own stake daily.
it is due to the coin age from 2 hours to 30 days maturity, it means it may take you as short as 2 hours or as long as 30 days to mint a block and produce a stake.
The problem is, i have receive the coin from ICO, and the transaction is showing in my wallet (Transaction ID: b66b27231971e870526390b2a4bd9941f8c71e445d6305c95e2ddf644c5ae17f), i haven't touch it and recently i want to test the send function or coin control feature, but i found out i can't do anything with the balance, i can't send it to another wallet or move it to exchange wallet, My wallet balance show 0.00 ERM while the received transaction from IPO show in recent transaction.
I suspect that is why my ERM never reach mature age.
try to open the console from the debug window and type the repairwallet command then restart you wallet, see if it fix your balance