Hello Alice-day
Thank you for your post and sorry for the late reply.
This is very strange, usually you can activate the ticket for the same day as well. Please make sure your App is up to date and if possible, activate the day in advance.
If you do activate it for the same day, please do it by calling us (0041 848 44 66 88, CHF 0.08/min), so that the operator can also send you a confirmation email.
Thank you and have a nice day.
EleonoraS