[R] Question:manipulating spatial data using combination of Maptools and Splancs

[kostas karis]

Hi,
I have a problem that concerns combination of the package Maptools and 
Splancs
I have 2 shapefiles that i want to manipulate (one of type point and one 
polygon).I import them in R using Maptools but then i can't estimate a 
quartic Kernel using Splancs. The package doesn't recognize the shapes 
(invalid points and poly argument).I don't know if this is an easy task but 
i have read both packages's manual and i can't find a liable solution. Thank 
u for your time.