SQL Exclusion?

Hello,

This statement  reports 9,765 items
select SYS.Netbios_Name0
From v_R_System SYS

This Statement reports 6,102 items
select SYS.Netbios_Name0
From v_GS_SoftwareFile SF
join v_R_System SYS on SYS.ResourceID = SF.ResourceID
Where SF.FileName LIKE 'MIV2LIB.exe'

This statement reports 0 what is wrong?
select SYS.Netbios_Name0
From v_R_System SYS
WHERE NOT EXISTS (select SYS.Netbios_Name0
From v_GS_SoftwareFile SF
join v_R_System SYS on SYS.ResourceID = SF.ResourceID
Where SF.FileName LIKE 'MIV2LIB.exe'
)

Thanks,

Dom

System Center Operations Manager 2007 / System Center Configuration Manager 2007 R2 / Forefront Client Security / Forefront Identity Manager