Make sure you reference the
longfield with geostats:
sourcetype=foo | geostats latfield=my_laitudet_field longfield=my_longitude_field count
Otherwise, Splunk will just look for fields called
lon. As @mtranchita mentioned, make sure you're on the visualizations tab and have selected the appropriate visualization type.
Note where it says "Cluster Map" as the visualization type:
I'm likely misunderstanding the question, but are you looking at the statics tab and not the visualization - or can you change the visualization type?
I think that the example from the command reference shows what you are describing.