Well, unfortunatelly I have not a masternode yet, just some thousands of coins.
However, now I have encrypted the wallet and even if I open it for staking only, it doesn't actually stake any more. Which could be the cause?
You have to unlock it for staking.
I know that and I HAVE unlocked it for staking. However if I put my mouse in the lower right corner of the wallet I can see that I am not staking because the "wallet is locked" even though I have unlocked it for staking. Anyone with the same problem?
You should understand that encrypting the wallet will make it stake is totally wrong, encrypting is like putting a key to your wallet nothing more & has nothing to do with staking or not. As for staking, it takes time according to the coins age & bla bla of those technical things, check back OP tos about staking, i'm sure you're missing something.
PS: usually staking need nothing but some certain amount (minimum) which differs according to the coins rules, your network weight (that' something crucial by he way) & also you need to leave your wallet open at least 12 hours +