How can I make MapAttributesForJoin being called

Hello!

I'm quite new to MIM so I assume this is a very basic question.

In the "Configure Join and Projection Rules" I have set these two rules
Mapping Group   Action                                     Metaverse Object Type
1                         Join                                          PersonT
homeDir              Direct                                       uid
2                         Join                                         GroupT
homeDir              Rules extension avdelningsID     avdelningsID

I have also this code 

void IMASynchronization.MapAttributesForJoin (string FlowRuleName, CSEntry csentry, ref ValueCollection values)
        {       
            switch (FlowRuleName)
            {
                case "avdelningsID":
                    string[] split = csentry["homedir"].Value.Split('-');
                    if (split.Length == 2)
                    {
                        values.Add(split[1]);
                    }
                    break;
             }
        }

In MAR agent for outbound.

Now to my question if I set a breakpoint just in the beginning of this method how can I make it being called.

//Tony