[R] date library and notched boxplots

[smestrella@juno.com]

I'm having problems using the date library with notched boxplots.  I have separate month, day, and year columns and would like to plot the columns as a date against other variables.  I have used the mdy.date(month,day,year) command before with plot(), but it doesn't seem to work with boxplot().  Instead of the dates along the x-axis, I get a list of numbers.  Maybe I have the code wrong?  I have used the help() menu in R, but with no success.

Can somebody please help?

Thanks,
Stephanie