At the moment your voicemail information will not show on your profile if any of the following conditions are true:
- You are paying to display your phone number
- A group phone number is appearing on your group page
- You are offering DirectChat and are 'Available Now'
- You have not recorded a voicemail greeting
- You have not ticked the 'Accept Voicemail' box on your Edit Profile Page.
It works this way by design, to encourage potential callers to actually call you, versus leave you a message.
More information on setting up your voicemail can be found here.