SignatureDoesNotMatch error

[paolini]

I followed instruction and executed the sample code. I get the following error:

Creating new bucket with name: python-sdk-sample-0937726b-7715-4eb0-a1f1-39ed163a1cd9
Traceback (most recent call last):
  File "s3_sample.py", line 37, in <module>
    bucket = s3.create_bucket(bucket_name)
  File "/Users/paolini/.virtualenvs/gpexe/lib/python2.7/site-packages/boto/s3/connection.py", line 621, in create_bucket
    response.status, response.reason, body)
boto.exception.S3ResponseError: S3ResponseError: 403 Forbidden
<?xml version="1.0" encoding="UTF-8"?>
<Error><Code>SignatureDoesNotMatch</Code><Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message><AWSAccessKeyId>AKIAIHETI7WQILDYCM2Q</AWSAccessKeyId><StringToSign>PUT


Sat, 23 May 2015 07:16:25 GMT
/python-sdk-sample-0937726b-7715-4eb0-a1f1-39ed163a1cd9/</StringToSign><SignatureProvided>vXnYgv6Ji5j+YkNxTH2tO6jW5u0=</SignatureProvided><StringToSignBytes>50 55 54 0a 0a 0a 53 61 74 2c 20 32 33 20 4d 61 79 20 32 30 31 35 20 30 37 3a 31 36 3a 32 35 20 47 4d 54 0a 2f 70 79 74 68 6f 6e 2d 73 64 6b 2d 73 61 6d 70 6c 65 2d 30 39 33 37 37 32 36 62 2d 37 37 31 35 2d 34 65 62 30 2d 61 31 66 31 2d 33 39 65 64 31 36 33 61 31 63 64 39 2f</StringToSignBytes><RequestId>4FCBBDBCC93DC696</RequestId><HostId>M1olgGhdOIVN60tgcltPj6FYFDg5AA+B1XyDMH5pT75JVBMBy/E8Cc4Nfroqm2a8</HostId></Error>