Apparently Access it's just weird

. It doesn't support count(distinct .. etc).
You could do this :
http://allenbrowne.com/ser-66.html.
Or, you could Have an inner select , and count that:
SELECT count(*) FROM
(SELECT DISTINCT [SV-5.NameA]
FROM ([SV-5] LEFT JOIN SFtoFD ON [SV-5].NAMEA = SFtoFD.NAMEB) LEFT JOIN SFtoSV4 ON [SV-5].NAMEA = SFtoSV4.NAMEB
WHERE SFtoSV4.NAMEB IS NULL AND SFtoFD.NAMEB IS NULL;) AS a