PowerMailChimp won't sync Marketing List subscribers to MailChimp List

Hi,

I'm trying to create a MailChimp blast on CRM online but I'm experiencing a syncing problem of my subscribers to the MailChimp Account. 

I've created a Marketing List "My Test Martketing List" and associated it with a MailChimp List. I added Members to my Marketing List and then clicked on "Sync Now". I found that "My Test Marketing List" has been added to the MailChimp List but with 0 subscribers. 

How can I sync my marketing list members to MailChimp List successfully ?

Thanks