Weird problem redirecting lattice graph to a file

Hello,

I am having this weird issue where I cannot send a lattice graph to a device
like pdf() or png(), but this only happens when the statement is inside a
function. For example, this works:

a <- matrix(0,5,5)
pdf("test.pdf")
levelplot(a)
dev.off()

But now, put the last three statements in a function (F(a)) and the pdf is
not produced. I tried replacing pdf with
trellis.device(device="pdf",file="test.pdf") and it still does not work.

Funny thing is that plot() or image() will work inside a function as
expected when re-directing to other devices, but not any of the lattice
functions.

Any ideas?

Thanks,

Jorge

Jorge A. Ahumada, Ph.D.
Technical Director, TEAM
Center for Applied Biodiversity Science
Conservation International
1919 M Street, NW Suite 600
Washington, DC 20036-3521
Ph: 202-912-1516

j.ahumada at conservation.org
http://www.teaminitiative.org/