[10.2.0.4] analyzing AWR report

Hi, Here's the Time Model Statistics part of my report :
My question is :
If DB CPU = 655 and total DB Time = 1900, How do you explain that the sum of the other roww is not equal to (DB Time - DB CPU).
Where could I find the detail of wait time (DB Time-DB CPU) ?

Rgds,

sql execute elapsed time	1,744.05	91.77
DB CPU	655.91	34.51
parse time elapsed	150.31	7.91
hard parse elapsed time	136.94	7.21
failed parse elapsed time	62.29	3.28
PL/SQL execution elapsed time	1.25	0.07
hard parse (sharing criteria) elapsed time	0.37	0.02
PL/SQL compilation elapsed time	0.07	0.00
connection management call elapsed time	0.06	0.00
repeated bind elapsed time	0.05	0.00
hard parse (bind mismatch) elapsed time