SQL 2012 :: Encrypting A Column On TDE Enabled Database

I have a database that is the publisher in transactional replication and also part of an availability group. I have put the pertinent certificates on all of the involved servers, and it is encrypted on all servers and operated as expected. However, we are adding additional security for personal data and we have targeted columns in multiple tables for column encryption. I have a master key and certificates that are stored in the master database. Following an example where I am to create the database master key:

-- Create database Key
USE encrypt_test;
GO
CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'Password123';
GO

But when I try to create a certificate on the database:

-- Create self signed certificate
USE encrypt_test;
GO
CREATE CERTIFICATE Certificate1
WITH SUBJECT = 'Protect Data';
GO

It get the following:
Msg 15151, Level 16, State 1, Line 1
Cannot find the certificate 'Certificate1', because it does not exist or you do not have permission.

Can I add a database certificate to an already TDE enabled database and if not to I create the symmetric key through the certificate located on the master database? And how will that effect decrypting the column values in stored procedures and function on the user database?