rbind problems with SpatialPolygonsDataFrame

R-sig-geo'ers:

I apologize that I can't provide the input data, but maybe the info
below can illuminate the problem.  Basically, I'm trying to rbind two
SpatialPolygonDataFrames together, but I'm getting a strange error:

'no method or default for coercing "logical" to "SpatialPolygons"'

Does rbind only work on SpatialPolygons (e.g. should I rbind the
SpatialPolygons and the data.frame separately, then piece them back
together afterwards?)

Note the "replacement" call was because I couldn't figure out how to
do.call(rbind) and pass along the "makeUniqueIDs=TRUE"

i=2
boundary_vectors=rbind(boundary_vectors,boundary_vectors_unmerged[[i]],makeUniqueIDs=TRUE)

Error in as(x, "SpatialPolygons") :
  no method or default for coercing "logical" to "SpatialPolygons"

class(boundary_vectors)

[1] "SpatialPolygonsDataFrame"
attr(,"package")
[1] "sp"

class(boundary_vectors_unmerged[[i]])

[1] "SpatialPolygonsDataFrame"
attr(,"package")
[1] "sp"

This was a single step from a larger looping I used in lieu of do.call:

class(boundary_vectors_unmerged)

for(i in (1:length(boundary_vectors_unmerged)))
	{
		print(i)
		if(i==1)
		{
			boundary_vectors=boundary_vectors_unmerged[[i]]
		} else
		{
			boundary_vectors=rbind(boundary_vectors,boundary_vectors_unmerged[[i]],makeUniqueIDs=TRUE)
		}
	}


--j

Jonathan A. Greenberg, PhD
Assistant Project Scientist
Center for Spatial Technologies and Remote Sensing (CSTARS)
Department of Land, Air and Water Resources
University of California, Davis
One Shields Avenue
Davis, CA 95616
Phone: 415-763-5476
AIM: jgrn307, MSN: jgrn307 at hotmail.com, Gchat: jgrn307