Help with a Lattice plot that fails with an empty unique combination

While using Lattice I received the following error.

Error in if (xx != 0) xx/10 else z/10 : argument is of length zero
In addition: Warning messages:
1: is.na() applied to non-(list or vector) in: is.na(x)
2: is.na() applied to non-(list or vector) in: is.na(x)
3: no finite arguments to min; returning Inf
4: no finite arguments to max; returning -Inf
5: NaNs produced in: log(x, base)
Can anyone point me in the right direction.

A traceback() shows that this is happening due to jitter() being called 
with a length-0 numeric. I have added a check in panel.stripplot. Until 
the next release, you can work around it by:


assignInNamespace("panel.stripplot",     
    function(x, y, jitter.data = FALSE, factor = 0.5,
             horizontal = TRUE, groups = NULL, ...)
{
    if (length(x) < 1) return()
    x <- as.numeric(x)
    y <- as.numeric(y)
    y.jitter  <-
        if (horizontal && jitter.data) 
            jitter(y, factor = factor) else y
    x.jitter  <-
        if (!horizontal && jitter.data) 
            jitter(x, factor = factor) else x
    if (is.null(groups)) panel.xyplot(x = x.jitter, 
        y = y.jitter, ...) else 
    panel.superpose(x = x.jitter, y = y.jitter, 
        groups = groups, ...)
}, "lattice")


Deepayan