SQL selects

We have a user trying to use SQL to format three fields for a vendor.
this works, although it is not as complete as desired:

SELECT dbmdc# as check,                                           
       decimal(dbmddt*10000.0000001-10299997997,11,0) FROM dbmtckp
       WHERE dbmcpy ='F' and dbmdc# between 26969 and 26999 
       and dbmddt > 1030000                                                     
      
SELECT statement run complete.                                    

this fails:

SELECT dbmdc# as check,                                           
       decimal(sum(dbmamt)*100,12,0),                             
       decimal(dbmddt*10000.0000001-10299997997,11,0) FROM dbmtckp
       WHERE dbmcpy ='F' and dbmdc# between 26969 and 26999 
       and dbmddt > 1030000                                                     
      
Column DBMDC# or expression in SELECT list not valid.             

Adding the sum function seems to cause a problem,
any clues?

TIA, 

Dan Rasch - because if the human species concentrated on the really 
important things in life, there would be a shortage of fishing poles!
IBM Certified twice....... but still a couple PTFs away from Nirvana.