Amazon S3 Permission Errors 403, simple upload of a text file

So I have been using several different tutorials in stackoverflow and they all seem to come to the same error: 403 Permission denied.

I am using python2.7 and boto on ubuntu 14.04.

Below is the code (without the keys and bucket name) and I would like to know why I am being denied access to my own bucket.

I created a user in IAM that has complete access to S3, and I set the permissions on the bucket to allow 'Everyone' to upload/download. I am using the correct keys because I copied and pasted them into the code.

Could this have something to do with bucket policy? Or is there something I am not aware of? I am new to this and only need this to upload and download text files on S3.

import boto
from boto.s3.key import Key
import boto.s3.connection

AWS_ACCESS_KEY_ID = ''
AWS_SECRET_ACCESS_KEY = ''
Bucketname = '' 
conn = boto.connect_s3(aws_access_key_id=AWS_ACCESS_KEY_ID,
       aws_secret_access_key=AWS_SECRET_ACCESS_KEY )

bucket = conn.get_bucket(Bucketname)