If you can't log in, please try the following.
Make sure you are using firstname.lastname as the username and your NHC email password.
Sign in to your New Horizons Google account https://www.google.co.uk/
(you may be signed in on another account. If so, logout and login using your NHC email address)
If you can't log in, then you are using the incorrect credentials. Use the Google password reminder to reset your password. Once you have reset the password try logging onto iamco.re with the same credentials. Note that if you use email on your mobile device or desktop mail program (Outlook etc), you may need to update the password that the device/program uses to connect to your NHC mail.