bug with item drops

so i have created a custom item gave it a lore and gave it a custom name and ench and now i am trying to make a mob drop it i write

Drops:
- Coin 1-10 1

but the mob only drops one every single time any idea ?

also
the mob will always drop 1 custom item in the matter of what i do like
- Coin
or
- Coin 1.4 1
-
- Coin 4 1
or
- Coin 4.1 1