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 one rare 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.