Load new game mode with server travel

I try to change the GameMode while changing the level with server travel. I use server travel in blueprint with execute console command node. In the command, I type “servertravel mapname?Game=pathtogamemode_C”. But it doesn’t work for me, new GameMode still doesn’t load. I encounter similar questions in the forum but none of them work for me. Any idea why it is the case?
Thank you in advance.