Hi Sophia,
Infotype just checks if amount entered is not exceeding a particular amont in one entry not what was entered in past added to current entry would exceed limit.
If this would have happened then rule was not at all required.
Infotype won't do the entries total. In such cases, infotype download report is run to check if amounts are exceeding or not and handled manaually.
Kindly also update the thread as helpful if solution being provided is of value and helps as i have not seen anything helpful in this thread by far based on what solution I am providing.
Thanks,
Ameet