Self-Service API Returning NetworkError

Question

I've been trying a number of different example scripts listed on the developer github page here, but they all seem to return errors.

from amadeus import Client, ResponseError

amadeus = Client(
    client_id='API_KEY',
    client_secret='API_SECRET'
)

try:
    response = amadeus.reference_data.locations.airports.get(longitude=0.1278, latitude=51.5074)
    print(response.data)
except ResponseError as error:
    raise error

This code block returns a network error amadeus.client.errors.NetworkError: [---]

(also, yes, I did actually use my api key and secret)

I'd really appreciate some help.