Unfortunately, you are one of two people that they are insisting is linked to another affiliate. Did you maybe visit the site through someone else's ads and forget about it? Even if you didn't download it through them, I think their software MAY use cookies to track you to that affiliate if you went their first
I've been able to get all the other missing credits resolved, except for you and the one other person, who realized he did go to their site through another affiliate first.
There's not really anything I can do.
The good news is for everyone else - if you signed up and PM'd me your info, unless I told you otherwise, you'll be getting paid later today.