Fallback Method Failing

I have configured the fallback sending method to use AmazonSES and does work when set as the main method yet I am getting the following message:
( ** Fallback ** ) Transaction failed: Expected parameter value, got “”

In Fall Back – Port 587 with TLS, although when its setup as the main method I am using Starttls. Just strange that I can get it to work when its the main sending method but when its the backup it fails.

Anyone know what may be going on?