Hi Elisabeth, I am having a similar problem to the one which you posted to the following link: https://stat.ethz.ch/pipermail/bioconductor/2013-February/050949.html did you ever find the solution, I am receiving the same error: In FUN(newX[, i], ...) : NAs introduced by coercion Any help would be much appreciated, Yours, Brian Caffrey MPIMG Berlin [[alternative HTML version deleted]]