I don't get taken to the login window
If, when you click the button to log in:
you don't see the login window or
you get taken straight to an "Authorisation Required" notice,
without any fields to enter your username and password,
then you may need to restart your web browser, or even your computer, tablet or smartphone. This will clear the old details they may have retained.
NB: For something like an iPad, just pressing the home button doesn't turn it off – it only sends it to sleep. Hold down the small button on the top of the tablet for a few seconds, and follow the instructions that appear. When it has turned off, use the same button to turn it on again.
I enter my username and password, but they don't work
If you get to the login window and have entered your username and password, but find they are not accepted, then:
a) check you entered them exactly as given. Remember they are case-sensitive.
b) if they still don't work, please email the webmaster.