Amazon MWS string to sign and signature: Python

I have to admit im very new to this so this might be a dumb question or I might be going around this completely the wrong way. Im trying to figure out the string to sign and Base64 HMAC signature. At this point I would like to verify that the code ive found works. Here it is:

import hashlib
import hmac
import base64

message = bytes("Message").encode('utf-8')
secret = bytes("secret").encode('utf-8')

signature = base64.b64encode(hmac.new(secret, message, digestmod=hashlib.sha256).digest())
print(signature)

I had the impression that I could copy the (string to sign) off of the scratchpad and replace it with "Message" and then paste in my secret key for "secret". However my output doesnt match amazon scratchpads signature. Can someone point out the error in my ways?