Hello, everyone!
We're sorry about the confusion. This is a recently released product, and we are still working on making it as user-friendly as possible.
What we believe is happening here is that someone has already linked your SEOmoz account to a Twitter account on Followerwonk. You can only be linked to one Followerwonk account, and it won't let you link another. We realize it isn't made clear that that is the problem, and we are working to redress that.
Richard, your SEOmoz account is already linked to @Rich94. Confetti, you are already linked to @NewsletterEx. Oleg, you are already linked to @MichaelMelen.
You are allowed to have multiple Twitter accounts under the same Followerwonk account, but you must go through a step to specifically authorize this. In the upper right of the Followerwonk page, there is a pulldown menu in which you can select "Add new Twitter account". Using this button, you can "merge" your Twitter accounts into the same Followerwonk account. If that account is linked to your SEOmoz account, then all the Twitter accounts will be.
Let me know if this makes sense and helps you!