The procedure 'sp_replicationdboption' cannot be executed within a transaction

Hi

I trying to do a merge replication of my DB.

When I execute this command:

use [xxx]


exec sp_replicationdboption @dbname = N'xxx', @optname = N'merge publish', @value = N'true'
GO

I'v got this messages:

Msg 15002, Level 16, State 1, Procedure sp_replicationdboption, Line 94
The procedure 'sp_replicationdboption' cannot be executed within a transaction.

What is a solution? I looking in this forum and google and still haven't the answer. Can anybody help me?