Making custom story and error pops up

[Sinthetic]

There is a ''story.png'' image in the folder.. :I Thank you for trying still

E: Forgot to mention, the error started to pop up after I copied the ''mapname.map'' file from desktop to the
map folder, because I couldn't see the .map file myself (but the mapeditor could still open it and I was able to play it) so I read some posts of this problem and the solution was to save the .map file to desktop and then copy it to
maps folder. So after I did that, the error started to show up :I