SQL Service Broker & Logical File Names
There are only 4 steps to enable service broker for a Database and non of them use logical file name as parameter 

Try this

USE MASTER
GO

IF EXISTS ( SELECT  is_broker_enabled, Service_Broker_Guid,*
            FROM    sys.databases
            WHERE   name = 'DB2'
                    AND is_broker_enabled = 0 ) 
BEGIN                    

    -- Step 1 ---  Rollback running transactions and brings the database in a single user mode.
    ALTER DATABASE DB2 SET SINGLE_USER WITH ROLLBACK IMMEDIATE


    -- Step 2 --- To avoid distributed conversation and OLD database GUID conflicts.
    ALTER DATABASE DB2 SET NEW_BROKER;


    -- Step 3 --- Set the is_broker_enabled flag to true  
    ALTER DATABASE DB2 SET ENABLE_BROKER;


    -- Step 4 --- Brings the database back to Multi user mode and allow shared locks\connections.
    ALTER DATABASE DB2 SET MULTI_USER WITH ROLLBACK IMMEDIATE

END