Message unable to send error

I’m a new programmer creating a game for my A-level course, I’m getting an error message and cant find/ fix the problem. its probably a simple fix if anyone could help

 main/scenes/main_menu.gui_script:12: Could not send message 'show_How_To_Play' from 'mainmenu:/mainmenu#mainmenu' to 'main:/how_to_play#script'.
stack traceback:
  [C]:-1: in function post
  main/scenes/main_menu.gui_script:12: in function <main/scenes/main_menu.gui_script:8>

Do you have a game object with id how_to_play with a script component with id script in a loaded collection with id main? And is that collection loaded?