Campaigns-Add other managers/admins to zoho campaigns

I created some campaigns, i need to allow other individuals in our CRM to get in and see the same campaigns I made and help manage them. How do I add other users from our zoho account? I tried adding them and I got a message saying "that email is all ready associated with an account. I did this - Settings > Manage Users > Add User > This email address has been already used in some other organization. So you cannot add/invite this user.

I also tried adjusting privileges.

Thanks In Advance

Joe