This error message could appear for a variety of reasons. Firstly, please ensure your childs school has got the correct mobile and email address assigned to your SchoolMoney account. If your school has more than one parent on record, it is worth checking with your school to see which parent is on the SchoolMoney system.
Unfortunately SchoolMoney support cannot help you gain access to the system and you must go through the school.
An easier alternative method to making payments to your childs school that does not require you to log in every time is available on the Google Play and Android App store which can be found here :