KeyError when merging

[kbrummert]

I get a KeyError when merging two data frames, even though I have confirmed that both have dt as a name and both are of the same data type.

df_hown.head()
Out[118]: 
           dt  hown_rt
0  1980-01-01     65.5
1  1980-04-01     65.6
2  1980-07-01     65.6
3  1980-10-01     65.6
4  1981-01-01     65.6

df_vcy.head()
Out[119]: 
           dt  vcy_rt
0  1956-01-01     6.2
1  1956-04-01     5.9
2  1956-07-01     6.3
3  1956-10-01     5.8
4  1957-01-01     5.3



df_hown.dtypes
Out[132]: 
dt          object
hown_rt    float64
dtype: object

df_vcy.dtypes
Out[133]: 
dt         object
vcy_rt    float64
dtype: object


# merge dataframes to create new one
df_merged = pd.merge(df_hown,
                 df_vcy[['vcy_rt']],
                 on=['dt','dt'])

...

KeyError: 'dt'