[R-sig-eco] Problem with Polygon

[momadou sow]

Hi,
I have a
matrix with 3 columns (Date, MeanArea and SdArea). I want to draw a figure showing
the variable MeanArea in terms ofthe
Date. 
But instead to use the variable SdAreaas
bar error, I want to use “polygon error”. I use this code but the output does
not seem good. 
>Poly<read.table("C:\\Users\\Documents\\AreaMonthly.csv",sep=";",dec=",",header=TRUE)
>Poly 
>y <-MeanArea 
>x <-SdArea 
>z <-Date 
>matplot(x,cbind(y,z),type="n") 
>polygon(c(x,rev(x)),c(y,rev(z)),col="grey50") 
Thank
you in advance