You wrote this code snippet to receive messages from an AWS SQS queue but it returns no messages:

You wrote this code snippet to receive messages from an AWS SQS queue but it returns no messages:

response = sqs.receive_message(QueueUrl=queue_url, MaxNumberOfMessages=5)
messages = response['Messages']
for msg in messages:
    print(msg['Body'])

What is the likely cause of the error?