I have a dataframe that looks like this:

```
    Capital Social  Mark    Porte
0   12345           B 
1   0               A
2   0               A
3   12345631        A

```

If `Capital Social == 0` and `Mark == A` I want to turn Porte into `Big`. So I'm running the following code:

```
df['Porte'].loc[(df['Capital Social'] == 0) & (df['Mark'] == 'A')]='Big'

```

However, when I run it, the result I get is just the same df:

```
    Capital Social  Mark    Porte
0   12345           B 
1   0               A
2   0               A
3   12345631        A

```

If I `print(df['Capital Social'].dtypes)` I get `Int64` as result.

If I `print(df['Mark'].dtypes)` I get `object` as result. I tried to run `df['Mark']=df['Mark'].astype(str)` but the result keeps being an object. Is this the problem or what am I missing?