Issue with selecting dataframe rows between two dates

Question

I am trying to select rows between a set date range but keep running into the same error. I tried all the methods described in this post with no luck.

Select dataframe rows between two dates

Here is my dataframe:

And this is the error I keep getting when trying to select dates:

Traceback (most recent call last):   File "X:/GIS/Projects/scripts/test.py", line 7, in <module>
    mask = (df['TransDate'] > '2017-01-15') & (df['TransDate'] <= '2017-12-20')   File "C:\Python27\ArcGISx6410.6\lib\site-packages\pandas\core\frame.py", line 1997, in __getitem__
    return self._getitem_column(key)   File "C:\Python27\ArcGISx6410.6\lib\site-packages\pandas\core\frame.py", line 2004, in _getitem_column
    return self._get_item_cache(key)   File "C:\Python27\ArcGISx6410.6\lib\site-packages\pandas\core\generic.py", line 1350, in _get_item_cache
    values = self._data.get(item)   File "C:\Python27\ArcGISx6410.6\lib\site-packages\pandas\core\internals.py", line 3290, in get
    loc = self.items.get_loc(item)   File "C:\Python27\ArcGISx6410.6\lib\site-packages\pandas\indexes\base.py", line 1947, in get_loc
    return self._engine.get_loc(self._maybe_cast_indexer(key))
    File "pandas/index.pyx", line 137, in pandas.index.IndexEngine.get_loc (pandas\index.c:4154)   
    File "pandas/index.pyx", line 159, in pandas.index.IndexEngine.get_loc (pandas\index.c:4018)   
    File "pandas/hashtable.pyx", line 675, in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12368) 
    File "pandas/hashtable.pyx", line 683, in pandas.hashtable.PyObjectHashTable.get_item (pandas\hashtable.c:12322) 
    KeyError: 'TransDate'