We are currently working to squash a little bug we have that is not allowing players that are on two or more teams, to answer Yes/No on the attendance e-mail and check-in or out to the game using this, instead, they get an "Event does not exist" message.
For the moment, players that are getting this error will need to check-in/out using the app.
We are working to fix this ASAP, sorry for the inconvenience.
Players getting "event does not exist" when checking in.