Could not start spark cluster on aws using spark-ec2 script - "AWS Could Not Verify Access Credentials Provided"

Question

I tried both of the commands below and set the env variables before running the scripts, but I was struck by the error "AWS could not verify valid access credentials." I do not think there are problems with the keys. I would appreciate any help to fix this. I am on an ubuntu t2.micro instance.

https://spark.apache.org/docs/latest/ec2-scripts.html

export AWS_SECRET_ACCESS_KEY=
export AWS_ACCESS_KEY_ID=

./spark-ec2 -k admin-key1 -i /home/ubuntu/admin-key1.pem -s 3 launch my-spark-cluster

./spark-ec2 --key-pair=admin-key1 --identity-file=/home/ubuntu/admin-key1.pem --region=ap-southeast-2 --zone=ap-southeast-2a launch my-spark-cluster

AuthFailure
AWS was not able to validate the provided access credentials

Traceback (most recent call last):
  File "./spark_ec2.py", line 1465, in <module>
    main()
  File "./spark_ec2.py", line 1457, in main
    real_main()
  File "./spark_ec2.py", line 1277, in real_main
    opts.zone = random.choice(conn.get_all_zones()).name
  File "/cskmohan/spark-1.4.1/ec2/lib/boto-2.34.0/boto/ec2/connection.py", line 1759, in get_all_zones
    [('item', Zone)], verb='POST')
  File "/cskmohan/spark-1.4.1/ec2/lib/boto-2.34.0/boto/connection.py", line 1182, in get_list
    raise self.ResponseError(response.status, response.reason, body)
boto.exception.EC2ResponseError: EC2ResponseError: 401 Unauthorized