Assign Network Manager an Online Scene with Script

Hello

I'm making a multi-player game and I need to select a map from script. The Network Manager don't want to assign the online scene selected by the script.

 GetComponent().onlineScene = m_sSceneName; 

I've been trying with Network.serverChangeScene but it don't work.

 GetComponent<NetworkManager>().ServerChangeScene(m_sSceneName);

Is there any other way to do it ?