Graduated Symbols Disappear on Map

[ameliabuttress]

I added some points to a map (shapefile created through google earth) and am able to change the symbology to different colors, but when I select graduated symbols, they disappear from the map.  Has anyone run into this?

[TracyDash]

I don't know how that is. I cannot find a way to edit symbology on Explorer- how did you change the symbol's colors?

Thanks!