Ok, so i've just made a flic animation at the res of 320-240. I add it to my game which is at 640-480 (editing the script to look like this "playflic 1,10" or something like that and it works fine. But if i put my game res up to 800-600 it comes up with the message "the backgroun is to small". Why doesn't it do this in 640-480 and how do i make it work at that higher res.
It's not about the flic animation but your room background image. If you change the resolution which your game is designed for (let's call it "base resolution") then you have to re-import backgrounds for all the rooms, since the engine doesn't support displaying a 640x480 room on a screen at 800x600.
That's why it is recommended to choose a desirable base resolution beforehand on starting a project.