I'm trying to use the Missile Map visualization, however, I only see the lines over a grey background, without the map that I normally see in say, choropleth maps. How do I use the same map as the choropleth map? I thought I could use the Splunk internal map tile url in this post  as the "customized" map tile (as my terminal is also not connected to the Internet), but it didn't work. Is the URL wrong? Thanks in advance.