Hi, all, The following error message was generated when I used "mva.pairs()" function to plot my data. "Error in simpleLoess(y, x, w, span, degree, parametric, drop.square, normalize, : recursive default argument reference" The same message was given when the example in the Help file was used. x <- matrix(rnorm(4000),1000,4) x[,1] <- x[,1]^2 dimnames(x) <- list(NULL,c("chip 1","chip 2","chip 3","chip 4")) mva.pairs(x,log=FALSE,main="example") Can someone help me out? Thanks. (R 2.01 and Bioconductor 1.5 packages were used.) Best, Puhong Gao, PhD Dev. Psychobiology NYSPI, Unit# 40 1051 Riverside Dr. New York, NY 10032 (212) 543-5014 [[alternative HTML version deleted]]