[AccessD] Invalid Operation - Query

When I try to run the attached SQL I get a message of invalid operation.
This query basically sums together 6 queries that each sum up some daily
data. Any thoughts as to why the error?

SELECT Gomez_Fld.ACTVDATE,
Gomez_Fld!SumOfVOLUME_SS+Halley_Emp!SumOfVOLUME_SS+Other_FortStockton!Su
mOfVOLUME_SS+Puckettl_Fld!SumOfVOLUME_SS+Waha_Fld!SumOfVOLUME_SS+[Warwin
k Fld]!SumOfVOLUME_SS AS [Total Gas]
FROM ((((Gomez_Fld INNER JOIN Halley_Emp ON Gomez_Fld.ACTVDATE =
Halley_Emp.ACTVDATE) I
NNER JOIN Other_FortStockton ON Gomez_Fld.ACTVDATE =
Other_FortStockton.ACTVDATE) 
INNER JOIN Waha_Fld ON Gomez_Fld.ACTVDATE = Waha_Fld.ACTVDATE)
INNER JOIN [Warwink Fld] ON Gomez_Fld.ACTVDATE = [Warwink Fld].ACTVDATE)

INNER JOIN Puckettl_Fld ON Gomez_Fld.ACTVDATE = Puckettl_Fld.ACTVDATE
GROUP BY Gomez_Fld.ACTVDATE,
Gomez_Fld!SumOfVOLUME_SS+Halley_Emp!SumOfVOLUME_SS+Other_FortStockton!Su
mOfVOLUME_SS+Puckettl_Fld!SumOfVOLUME_SS+Waha_Fld!SumOfVOLUME_SS+[Warwin
k Fld]!SumOfVOLUME_SS
ORDER BY Gomez_Fld.ACTVDATE;

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number of electrons were terribly inconvenienced. 



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