It seems to be an 2.6.1 Version problem. I tried to use http://umfragen.sowi.uni-mainz.de/CRAN/bin/windows/contrib/2.2/DBI_0.1-10.zip with 2.6.1 and 2.2.0 It is working with 2.2.0 (build under R Version 2.2.1) Knut