DKIM Enabled email Virtualmin/Amazon EC2

Hello, This is a small project to have our email servers setup to use DKIM so our messages are not being flagged as spam. We are running virtualmin on EC2 and all DNS is being handled by route53. I have milter installed and have tried enabling the DKIM but my test emails to the DKIM verification are telling me that theres no signature in the emails. I'm looking for someone that has done this before and knows what they are doing, please have at least 20 feedbacks. Thank you for your interest in this project