There are many reasons why you might not be able to login to the app, some of which are outside our control, e.g. the internet is currently not accessible from your device.
Assuming you have a stable Internet connection on your device then the biggest cause of login failures is the use of the wrong username and password - we all get them wrong sometimes :-)
Did autocomplete on your device change what you typed in?
Is CAPS LOCK on.?
Navigate to the website and try the same crendentials there - do they work there (the app uses the same authentication system so if it works for one it should work for the other)
If you can't login into the website either then we suggest you use the 'Forgotten Password' link on the Login page to reset it. This will send an email to your registered email address so make sure you have access to your Inbox and follow the instructions.
If you CAN login to the website but still cannot login to the app then please contact us via our Contact Page providing your registered email address but NOT your password. We will investigate as quickly as we can.