help me for Mob (urgen)

hi all i have some trouble with my server, im add 5 item at Raid Bos but just 1 item can drop, and 4 item never drop. im use file 1.4.6 file server, sory my bad english, please help me and dont blame me because im newbie, if u have tu torial link please post at here my friend ^^ i hope u can help us ^^ thank yu verymuch

code item = xxxxx
rate = 1

1= 100%
if you want to make 4 item
the rate must like this
code item = xxxxx
rate = 0.25
code item = xxxxx
rate = 0.25
code item = xxxxx
rate = 0.25
code item = xxxxx
rate = 0.25

i hope can that clue can help you

ok i will try thank you