[R] ggplot2; dot plot, jitter, and error bars

[Juliet Hannah]

With this data

x <- c(0,0,1,1,2,2)
y <- c(5,6,4,3,2,6)
lwr <- y-1
upr <- y+1
 xlab <- c("Low","Low","Med","Med","High","High")
mydata <- data.frame(x,xlab,y,lwr,upr)

I would like to make a dot plot and use lwr and upr as error bars.
Above 0=Low. I would like there to be
some space between the 5 and the 6 corresponding to Low so I tried jittering:

p <- ggplot(mydata, aes(x=x, y=y))
p+geom_point()
p + geom_jitter(position=position_jitter(xjitter=2))

But I obtained this error:

Error in get("new", env = PositionJitter, inherits = TRUE)(PositionJitter,  :
  unused argument(s) (xjitter = 2)

Any suggestions on how to plot this. I could create the separation in
the x-axis (0,0.2,1,1.2,2,2.2). If so,
how could I relable the axis ("Low","Med","High") in ggplot2.

Thanks for your help.

Juliet