It's quite rare that this is anything other than an issue of incorrectly entering it. To make sure its not simply an issue of misreading a O for a 0 or similar, please try copying and pasting them, making sure that you don't pick up and leading or trailing spaces both in the copying and in the pasting actions. Let us know.
It's happened to me to several times when I tried v3. The user name and password were already entered, but the tray icon turned red on occasion. It can be entered exactly with the same results as invalid. IIRC, a reboot solved the problem.