How to create a treasure map:

Use the right click menu, Treasuremap → Create random treasuremap. This creates a map linked to a chest, spawns the chest, and gives it all locations. If you just use the create menu it will be basically a blank map set to -1 -1 which wont work.

If you want to create a rare map you also create one from the create menu, check the Set Data on the random generated one, and use that Data 1 to put into the create menu map's Data 1, then destroy the random generated one. Verify it works by right clicking it as a GM and Teleport to Treasure.