MS Access 2010 joining with sum - sql

Question

I am trying to combine two tables but my results are showing incorrect data from one table.
One example is my first table has the following:
PositionCode AcctUnit BudgetFTE
JDFF HRT 2
my second table does not contain any record for PositionCode=JDFF and AcctUnit=HRT however I get the following results with running the query below:
PositionCode AcctUnit BudgetFTE ActualFTE VarianceFTE
JDFF HRT 2 1 -1
sql code:
SELECT
b.PositionCode,
b.AcctUnit,
e.POSITION,
e.HM_ACCT_UNIT,
b.FTE AS BudgetFTE,
sum(e.FTE) AS ActualFTE,
sum(e.FTE) - b.FTE AS VarianceFTE
FROM
QryBudgetRollUp AS b
LEFT JOIN ActiveEmployees AS e ON
( b.PositionCode = e.POSITION ) AND
( e.HM_ACCT_UNIT = b.AcctUnit )
GROUP BY
b.PositionCode,
b.AcctUnit,
e.POSITION,
e.HM_ACCT_UNIT,
b.FTE,
e.FTE - b.FTE
sample data:
QryBudgetRollup
PositionCode AcctUnit FTE
JDFF HRT 2
VIPP HRT 1
HROPSA CMP 1
ActiveEmployees
C E CE LAST_NAME FIRST_NAME EMP PROCESS HM_ACCT_UNIT D POSITION D;P' Date SC Expr1013 AP PG HC FTE PE
2 2343 22343 Doe John FT CHRE CMP CMP HROPSA CMP;HROPSA 2/15/1999 H $20.00 $40,000.00 4 1 1 $4,000.00
2 2515 22515 Jetson George PT CHRE CMP CMP HROPSA CMP;HROPSA 4/22/2014 H $10.00 $20,000.00 2 1 0.5 $2,000.00
4 18 418 Doe Jane FT CSIS HRT HRT VIPP HRT;VIPP 11/1/2002 S $40.00 $80,000.00 7 1 1 $8,000.00
Desired Query Results
PositionCode AcctUnit BudgetFTE ActualFTE VarianceFTE
JDFF HRT 2 0 2
VIPP HRT 1 1 0
HROPSA CMP 1.5 2 -0.5