Here is a modified .capx that, I hope, does what you expected. The tilemap you're using is just here for coordinates, as the creation of "ressource" object doesn't affect it. "Ressource" object is not a tile and doesn't modify tilemap on creation, so you don't have to test if the tilemap is empty under the pointer, but only if the pointer already overlaps with the object. If not, you can create one at the desired position.
I also modified the coordinates for object creation on the tilemap. The origin of your 32x32 sprite is in the top left corner, so you have to create it at -16/-16 pixels from the position given by the expression TIlemap.SnapX and SnapY.https://www.dropbox.com/s/vi4gtp4xwc9fnqn/tilemapExample1.capx?dl=0