I did everything they said in the tutorial on unreal engine how to create a main menu. My scripting is exactly the same like in the video. Still it doesn’t work when i click start game. 
some people said on other posts that it is because of the positions of the map. I really don’t know what i did wrong pliz help! fast respond pliz i’m in a hurry.
(ps: English is not my native language)
Got the same issue and verify theses couple things…
In your project settings, Maps&modes, game default map should be the one for mainmenu.
In your mainmenu level, (under world settings) you need to select a different gamemode BP then your level.(HUD class)
Make sure the starting level is exactly spelled the same!
Hope this helps 