The MYDIGIPASS application uses a time-based algorithm to generate codes. If the time on your mobile phone deviates from the time on the MYDIGIPASS servers, you will not be able to log in. This is also known as clock skew and may occur if you are crossing time zones, e.g. during air travel.
If this occurs, use the Synchronize Time button. MYDIGIPASS uses GMT, which stands for Greenwich Mean Time. GMT is in the same time zone as Coordinated Universal Time (UTC).