[R] a "date" x-axis in a xyplot

[jass at in.gr]

Dear all,

In the x-axis of a xyplot I define dates ,for example 01-10-2007 instead of numbers, in a range of 77 days. I would like in my output to have the whole date as a point. When I plot it, then the output is a big mess! I can not distinguish anything; the result is a thick, black line of overlapping dates.
Is there any solution so I can really distinguish and see clearly the dates in the x-axis?

Thanks in advance!

Ismini