Marker outside the map

[gabboraron]

I want to place markers dynamically from a JSON file, but some of them appear outside the map as this screenshot shows: https://pasteboard.co/J3WZVcR.png

My code:

	def add_map_markers(self):
		for line in range(0,len(data['positions'])):	
			print(str(line)+" - ")
			for idx in range(0,len(data['positions'][line]['poslist'])):
				print("\tX:"+str(data['positions'][line]['poslist'][idx]['X']))
				print("\tY:"+str(data['positions'][line]['poslist'][idx]['Y']))
				
				marker = MapMarkerPopup(lat= data['positions'][line]['poslist'][idx]['X'], lon=data['positions'][line]['poslist'][idx]['Y'] )
				marker.add_widget(Button(text="Description: "+data['positions'][line]['description']))
				self.add_widget(marker)

with this JSON:

{
"last modification date": timestamp, 
"positions": [
	
		{"poslist": [{"X": 1, "Y": 2}], "photos": [], "description": "", "name": ""},
		{"poslist": [{"X": 3, "Y": 4}, {"X": 5, "Y": 6}], "photos": [], "description": "", "name": ""}
	
]}

How can I block this bad behaviour of the map?