Same query different result

I have this query

Code:

---

SELECT

InputTable.Year,
AddressBook.Summary,
AddressBook.ID1,
First(AddressBook.TypeOfSchool) AS FirstOfTypeOfSchool,
Max(IIf([TypeOfSchool]="First Degree","Second Degree",[TypeOfSchool])) AS TypeOfSchool,
AddressBook.Science,
Count(InputTable.Sex) AS CountOfSex,
Sum(IIf(([YearFinished]-[FirstYearEnrolled])<=([YearsLong]-Int([FirstSemester]/2)),1,0)) AS WithingRange

FROM InputTable
INNER JOIN AddressBook
ON (InputTable.Code = AddressBook.Code) AND (InputTable.SubCode = AddressBook.SubCode)
GROUP BY
InputTable.Year,
AddressBook.Summary,
AddressBook.ID1,
AddressBook.Science;

---

A year ago, I had two MS Access installations. I think the old Access got broken and then it needed to reinstalled.
A year ago, that same query was listing one result. However when I run it now, it produces different result.

Could there be some issue with MS Access, going from lower to upper version, or having two Access installed on the same machine?

Something fishy in

Code:

---

Sum(IIf(([YearFinished]-[FirstYearEnrolled])<=([YearsLong]-Int([FirstSemester]/2)),1,0)) AS WithingRange

---

Simply said, this query should split the input table data in two sets, one where students finished school within the possible longevity of the school and second, students needed more years to finish the school than the school lasts.

So a year ago, i got say 2500, now when i run it i get 2000 for students finished within the longevity of the school, and those 500 go into the set for student who didn't finish in time.

The Access version should not be a factor. More likely it is the data, and the additional elapsed year causing the results you are seeing. Without any data to analyze, it would be difficult for us to provide any details or run any tests.

I turned out, nothing was wrong with the calculation itself. The table on which we were running the query had changed data and so, different result.