Level sets not opening

[MilkyWayWishes]

I'm going to assume you're using TW (Tile World), if that's the case then when you add a DAT file (a typical levelset) to the data folder, you also have to create a corresponding DAC (info file) in the sets folder. I recommend opening one of the included DAC files to see what you need to copy and change for a new levelset.

Alternatively you could just add the DAT file to the sets folder itself, but that only allows it to be played in one ruleset.