I get this error message when starting the game, after installing your mod (I used to get it with previous version of your mod as well):
After clicking "Ok" the game starts properly.
Edit:
I run my game in 1600 x 900 resolution, so I installed MaskMap 1600 x 900. Yet the stamp on my map is egg-shaped:
This is the order I installed the mod in:
Also I think that the mission orders button/icon (in orange circle on my screenshot) doesn't fit here aesthetically. It looks Microsoftish, doesn't go well with the filthy map looks or the other "hand-written" icons (ports, airports, destinations).