Why doesn't a date match the format?

```
>>> import datetime
>>> dt1 = "9/1/2014 0:00"
>>> datetime.datetime.strptime(dt1, "%m/%d/%y %H:%M")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_strptime.py", line 325, in _strptime
    (data_string, format))
ValueError: time data '9/1/2014 0:00' does not match format '%m/%d/%y %H:%M'

```

And this one either:

```
>>> datetime.datetime.strptime(dt1, "%d/%m/%y %H:%M")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/_strptime.py", line 325, in _strptime
    (data_string, format))
ValueError: time data '9/1/2014 0:00' does not match format '%d/%m/%y %H:%M'

```