When plotting as spatialDataFrame with a factor as the first column and many levels you get the error "plotGoogleMaps enable to start device png".
What's wrong?
The problem is that it is trying to plot all the levels and the legend gets tooooo long. You should try to use a more meaningful column for the legend.
I created a fork that fixes this and other issues (some values in the data.frame could prevent plotGoogleMaps from plotting) : https://bitbucket.org/cmbce/plotgooglemaps. It is easy to install with devtools.