Custom Campaign Not Beginning

[Decimax]

I've attempted to create a custom campaign, but whenever I try to launch it in the custom campaigns menu, I get the screenshot error down below, where there's only a back button and it doesn't load the first map. Is there something I need to do in order for it to work?

 

[Mechanical Man]

apparently the button is not visible

 

[Daffa]

Campaign Editor -> second tab -> make a button