this error occure while I am executing my query like:

Code:
select EMPNAME,A.EMPCODE,B.MACHINEID,EMPTYPE,PUNCHTIME,punchdate,sum(Amount)'Total Amount'  
from B,A,C 
where A.EMPCODE=C.empcode 
and  C.machineid=B.machineid 
and ( punchdate >=28/08/2012 and punchdate<=30/08/2012  )
and ( punchtime>=08:00 and punchtime<=18:00 )
and A.EMPCODE LIKE  '%'  
group by EMPNAME,A.EMPCODE,
...