[R] lines(aline, type = 'b', col = "blue) does not work for POSIXct plot.

[John Jaynes]

Hello,

x <- ISOdate(2003, 4, 1:30)           # POSIXct vector
y <-c(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30) 
aline <- c(30,29,28,27,26,25,24,23,22,21,20,19,18,17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1)
plot(x, y, xaxt = 'n', main = 'Number of Stuff for the Project, April 2003', xlab = 'Report Time', ylab = 'Number of Stuff', type = "b", col =  "purple")
axis.POSIXct(1, x)
lines(aline, type = "b", col = "blue")

These commands only produce one plot line on the resulting graph. Similar commands without the POSIXct lines 
generate the expected additional line on the plot, using the "lines" command. Any help on producing this additional 
line, while using POSIXct modifiers,  will be greatly appreciated, as I have yet to find a book on this Very interesting 
R Language, that would answer such useful minutiae.

Appreciatively,

John