R help - Sep 2003 - plot.ts doubt

Hi,

I'm ploting a multivariate time series but I want to change the y
labels. I've tried with ylab but I get an error
> plot(hke.ts,ylab=letters[1:5])
Error in plot.ts(x[, i], axes = FALSE, xlab = "", ylab = "",
log = log,
:
        formal argument "ylab" matched by multiple actual arguments

I've tried to use xy.labels but I also get an error
> plot(hke.ts,xy.labels=letters[1:5])
Warning messages:
1: parameter "xy.labels" couldn't be set in high-level plot()
function
2: parameter "xy.labels" couldn't be set in high-level plot()
function
3: parameter "xy.labels" couldn't be set in high-level plot()
function
4: parameter "xy.labels" couldn't be set in high-level plot()
function
5: parameter "xy.labels" couldn't be set in high-level plot()
function
6: parameter "xy.labels" couldn't be set in high-level plot()
function
7: parameter "xy.labels" couldn't be set in high-level plot()
function

What am I missing here ?

Regards

EJ