You may see an error regarding the day range on the diary. This is because you have restricted this user to only view certain days in the diary.
To rectify this, go to your company settings, open 'Users' and view the user that is having issues. Go to the mobile settings tab and change the number of days using the dropdown.
If you select --Please choose-- from the list it will set the boundary to infinite days and the user will not be restricted in any way with historical or future events that they can see in the diary.