Getting different results from the string constructor

[hnadra]

My local time is "America/Chicago" (UTC-06:00).

new timezoneJS.Date(2013, 00, 01, "America/New_York").getTime() => 1357016400000 (correct)
but:
new timezoneJS.Date("01/01/2013", "America/New_York").getTime() => 1357020000000 (incorrect)

Also:
new timezoneJS.Date(2013, 00, 01, "America/Los_Angeles").getTime() => 1357027200000 (correct)
but:
new timezoneJS.Date("01/01/2013", "America/Los_Angeles").getTime() => 1357020000000 (incorrect)