Cannot drop a publication due to the missing owner of the database

Scenario: 

Drop a publication

Problem:

-- Dropping the transactional publication

USE [AdventureWorks2012]
EXEC sp_droppublication @publication = N'AdvWorksProductTrans'
GO


Msg 15517, Level 16, State 1, Procedure sp_replcmds, Line 1

Cannot execute as the database principal because the principal "dbo" does not exist, this type of principal cannot be impersonated, or you do not have permission.

Solution:

I run as CK-PC\CK (an admin). The publication is for a table on the AW2012 database. When I check the owner of the AW2012 database, it is empty. I select CK-PC\CK as the owner for the database. Now I can drop the publication.