I’m not sure if this has already been posted somewhere, however as some users are having difficulty with it still (example: http://devforum.roblox.com/t/account-re-linking-problem-on-the-devforum/46022) I will put this here.
devforum.roblox.com doesn’t support accounts being associated with more than one email, and will direct you to a page which will give you the option to re-link your account. Upon attempting to re-link, you will be told to contact an administrator.
Easy solution to this is removing any other accounts which may be associated with your primary’s email from the address.
Sorry if this has been posted somewhere (couldn’t find it using search), but this may be helpful to others in the future.