[R-sig-Geo] error using filename argument with focalFilter() in package raster

[William McCoy]

I have a raster DEM loaded in R and I am using the raster package.  My 
DEM is called lakeside:

 > library(raster)
Loading required package: sp
raster version 1.5-8 (20-September-2010)
 > lakeside
class       : RasterLayer
filename    :
nrow        : 341
ncol        : 321
ncell       : 109461
min value   : 1288.399
max value   : 1704.749
projection  : +proj=utm +zone=12 +ellps=WGS84 +datum=WGS84 +units=m 
+no_defs +towgs84=0,0,0
xmin        : 344459.7
xmax        : 347669.7
ymin        : 4532817
ymax        : 4536227
xres        : 10
yres        : 10


When I use the focalFilter function with a filename argument, I get the 
following error:

 > xslopeLS <- focalFilter(lakeside, matrix(filtHorn, nrow = 3)
+ /(8*xres(lakeside)), filename = "xslopeLS")
Error in .local(object, values) :
   setValues no longer supports setting rows of values


However, if I call the same function without the filename argument, it 
seems to work fine:

 > xslopeLS <- focalFilter(lakeside, matrix(filtHorn, nrow = 3)
+ /(8*xres(lakeside)))
 > xslopeLS
class       : RasterLayer
filename    :
nrow        : 341
ncol        : 321
ncell       : 109461
min value   : -1.468210
max value   : 1.196593
projection  : +proj=utm +zone=12 +ellps=WGS84 +datum=WGS84 +units=m 
+no_defs +towgs84=0,0,0
xmin        : 344459.7
xmax        : 347669.7
ymin        : 4532817
ymax        : 4536227
xres        : 10
yres        : 10


Here is my filter:

 > filtHorn
[1] -1 -2 -1  0  0  0  1  2  1


And here is my sessionInfo():

 > sessionInfo()
R version 2.11.1 (2010-05-31)
x86_64-redhat-linux-gnu

locale:
  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
  [5] LC_MONETARY=C              LC_MESSAGES=en_US.UTF-8
  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] raster_1.5-8 sp_0.9-69

loaded via a namespace (and not attached):
[1] grid_2.11.1     lattice_0.19-11


Any idea what I'm doing wrong?

Thanks for your help,
Bill

-- 
William D. McCoy
Geosciences
University of Massachusetts
Amherst, MA  01003