R help - Nov 2004 - problem with usepackage{} in Sweave under Quantian

dear expeRts,

if i try to create a .tex file under Quantian 6.9.1 with sweave the 
command \usepackage{.../texmf/Sweave} will not added and the following 
compilation to a .pdf file failed. if i add the \usepackage line by 
myself all is going right. so what i am doing wrong because under mac os 
x 10.3 the \usepackage{} line is added automatically by sweave? In both 
cases i used xemacs/ess and R (all in the newest versions) to create the 
files.
thanks in advance for helping.

best wishes
andreas