u have to set "drop"s for the bags like this and make effect on 42, check ur files for some txt datas... i dont remember the file name but there u have to change wich drop grade and u can put in item ID, chance, if you do this then it will work
EDIT: File is here: SERVER-> PSM_Client -> Bin -> Data -> ItemCreate
just put one more [ItemCreate] inside and save this, take an example from the itemcreate's above like:
[ItemCreate_69] <- new grade item
339 <- grade 1000 <- Chance
and then save it and change this in the item.sdata (dont change the effect, effect should be on this items always 42! there is another slot for it (sry don't remember name q.q)