Error using print with double quotes

[Klaudioz]

I'm getting an error running:

print("Hello world")

If I run with single quotes, there is no error:

print('Hello world')

This is the error (I can't copy it)

[Klaudioz]

The same happens with dictionaries:

Running this:

ages = {"Peter": 10}
print(ages["Peter"])

I get: NameError: name 'Peter' is not defined.

Running this I don't have any issue.

ages = {'Peter': 10}
print(ages['Peter'])