Why jython doesn't import External Jar?

Question

I'm working on Jython, but I have a big problem, Jython doesn't import external jar file

This is the error:

>>> import sys
>>> sys.path.append('home/francesco/documents/jars/spigot.jar')
>>> from org.bukkit import *
    Traceback (most recent call last):File "<stdin>", line 1, in <module>
    ImportError: No module named bukkit

What can I do to resolve it?

Jython version = 2.7.0