It sounds like you have selected the 'player starting location' overlay, but you haven't selected a (player#/civ/random). In C3C I believe it's under map settings at the bottom where you assign a current player. You can right-click and alter the settings of the starting location once it's assigned, so you don't have to keep changing players after each location is set - but you do need to have any player set to actually place the location.
If that's not the answer, the other thing that causes pings is when the tile you're trying to place the starting location on can't support a starting location. this is not likely the case unless you modded the terrain heavily. If so, check your terrain settings.