Hello I've tried this procedure for staking:
You need to unlock the wallet, not un-encrypt it. Here are the instructions to unlock your wallet for staking while keeping it secure and encrypted
To start Staking whilst retaining the security of your wallet, go Help>Debug Window. Now select the Console tab.
Type the following at the bottom: walletpassphrase YourPassphrase 9999999 true
Replace the YourPassphrase with your own passphrase. (the encryption password you added earlier on) The 9999999 relates to the amount of seconds that you wish to leave the wallet open for staking. Once you have added this hit Enter.
It's not working for me..i keep getting this code:

Error: The wallet passphrase entered was incorrect. (code -14)
That means you entered the wrong password...
They use "passphrase" instead of password and it must be at least 10 characters long for it to take