Hi, I tried to plot the mismatch values of a probset, but got the message > plot(ps[[1]],which="mm") Error in range(c(f(x)), na.rm = TRUE) : couldn't find function "f" I think there should be a mistake in plot.ProbeSet function > plot.ProbeSet function (x, which = c("pm", "mm"), xlab = "probes", type = "l", ylim = NULL, ...) { which <- match.arg(which) if (which == "pm") f <- getMethod("pm", "ProbeSet") ----> else g <- getMethod("mm", "ProbeSet") if (is.null(ylim)) ylim = range(c(f(x)), na.rm = TRUE) if is.na(xlab)) xlab = "probes" matplot(f(x), xlab = xlab, type = type, ylim = ylim, ...) } It should be else f <- getMethod("mm", "ProbeSet") Thank you very much. Kind Regards, Kai Kai-Ming Chang AstraZeneca, Alderley Park