[R] map population density

[Barbara Diane-Spillmann]

dear all,

i?m trying to plot a map of population density in german communities by 
using shape files.
to plot the polygons is not the problem but as soon as I want to add the 
population data to the map I get the following message:

Fehler in if (attr(theMap$Shapes[[ii]], "nParts") == 1) { :
Argument hat Länge 0

My population data are either in form of a csv file or a column of the 
dbf file. either possibility gives me the message above.
what does R want to tell me?

thank you for your help

barbara