[R] Error in X11(paste("png::", filename, sep = ""), width, height, pointsize unable to start device PNG

[Vincent Deng]

Hi,
I got this error while using png() function in RedHat 9.0.

"Error in X11(paste("png::", filename, sep = ""), width, height, pointsize
unable to start device PNG"

It looks like the system lacks some library for graphics. Can anyone
tell me which rpm I should install to have png() function work with
out problem?

Thanks ...