[R] "pos" in panel.text

[Allan Sikk]

Hi,

I need to vary the placements of data labels but I cannot assign a 
vector to "pos" option. Any vectors work fine with "cex", for example. 
What could be the problem here?

xyplot(Npop~Narea, data=size,
scales=list(x=list(log=TRUE), y=list(log=TRUE),
xlab=expression(N[A]), ylab=expression(N[P]),
panel=function( ...) {
     panel.lines(..., type="l", col.line="black", lwd=.25)
     panel.xyplot(..., type="p", col="black", cex=.5, pch=20)
     panel.text(..., lab=t, cex=.5, pos=c(4,2))
})

Many thanks,
Allan