"Error in colnames" when merging xts sets - r

Question

I am trying to make an irregular multivariate time series regular. I am doing this by merging the irregular time series (one measure every 7 days) with a regular "NA" filled time series (daily measures) as suggested by:
- Joshua Ulrich here.
- Dirk Eddelbuettel here.
When I try this method for multivariate time series, I get the error:
"Error in colnames<-(*tmp*, value = c("C.1", "C.2", "C.1.1", "C.2.1" : length of 'dimnames' [2] not equal to array extent"
My question is 2 fold:
How can I merge these two xts data sets without getting this error?
Is there a "better" way of making an irregular multivariate time series regular? I guess I was expecting to find a method in the xts package, but could not find one.
Code to Reproduce Error:
require(xts)
set.seed(42)
# make irregular index
irr_index <- seq(from=as.Date("2010-01-19"), length.out=10, by=7)
# make irregular xts
irr_xts <- xts( x= matrix( data= rnorm(20), ncol= 2,
dimnames= list(c(1:length(irr_index)),
c("C.1", "C.2"))),
order.by= irr_index)
# make regular index
reg_index <- seq(from=as.Date(start(irr_xts)), to=as.Date(end(irr_xts)), by=1)
empty <- xts(matrix(data = NA,
nrow = length(reg_index),
ncol = ncol(irr_xts)),
reg_index )
reg_xts <- na.fill(merge(irr_xts, empty), fill=0)
In practice my real data are sporadic, sometimes daily, sometimes skipping several days. My approach is to normalize all data to 1 observation per day with 0 for days with missing values.
Thanks in advance.
EDIT:
Here is my sessionInfo() as requested:
R version 3.0.2 (2013-09-25)
Platform: x86_64-w64-mingw32/x64 (64-bit)
locale:
[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252 LC_MONETARY=English_United States.1252 LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] xts_0.9-7 zoo_1.7-10
loaded via a namespace (and not attached):
[1] grid_3.0.2 lattice_0.20-24 tools_3.0.2

Answer 1

This works fine for me, I just follow Joshua Ulrich link :
empty <- xts(,reg_index ) ## No need to set coredata to create empty xts
merge(irr_xts, empty, fill=0)
C.1 C.2
2010-01-19 1.370958 1.30487
2010-01-20 0.000000 0.00000
2010-01-21 0.000000 0.00000
2010-01-22 0.000000 0.00000
2010-01-23 0.000000 0.00000
2010-01-24 0.000000 0.00000
.....