Get Contact lists by Contact object

I am just trying to get a list of contactList objects where a  contact is added. 

In the code, the secondary contact is already in one list and I am trying to grab the name or id of the Contactlist from the code using below code but  secondary.MarketingSettings.ContactLists is null   :

 

           NamedIDDelta[] secondaryContactLists = secondary.MarketingSettings.ContactLists;

  

I can't think of why it is null. Please help.

 

Thanks,

Bishnu