I have tried to compile the code in this example from Political map in LaTeX following the latex->dvips->ps2pdf sequence but in the very first stage (latex compilation) I got the error message
!keyval: showgrid undefined
\KV@err #1->\errmessage {keyval: #1}
I am using an updated MikTeX 2.9 installation on Windows XP. Anyone could possibly help on this issue? Thanks so much in advance.