No marker on the map once changed the Gmap API key

the gmap was tested ok in my localhost test server (assigned the MAP API key for the localhost) , then I deployed to the host server and also changed to a new MAP API key for the live site, but then the map generated do NOT have the marker... The config remains the same as the localhost test server. Why is that? Is there anything that I need to do or adjust? Please help and advise.