Confused about a list.sort()

[Amy G]

I have a list of numbers... actully I have two lists, List 1 is a list of
number strings and List2 is one of numbers.

List 1 example:
List1 = [ '20040124123000', '20040124123001', '20040125012456']

List 2 example:
List2 = [ 20040124123000L, 20040124123001L, '20040125012456L]

When I try either:
List1 = List1.sort ... or
List2 = List2.sirt

and then...
print List1... or
print List2

I get None.

Why is this?
How do I remedy this problem?