If you can’t log in the first time, you should check caps-lock and number-lock and try again and take your time.
If you can’t log in the second time, you should check that you are entering the correct details. If in doubt use the ‘forgotten password‘ link under the log in.
If you fail a third time, assuming you have used the same (correct) username each time, your account will be disabled for 30 minutes, then automatically enabled.
This is a necessary measure to protect the platform from repeated false login attempts.