fun.aggregate=mean in reshape

You can use aggregate:

aggregate(data[,c("ozone", "solar.r", "wind", "temp")],
list(month=data$month), mean)

On 12/02/2008, [Ricardo Rodriguez] Your XEN ICT Team <webmaster at xen.net 

wrote:
Hi all,

We are facing a problem while introducing ourselves to Reshape  
package
use. Melt seems to work fine, but cast fails when we use mean as
fun.aggregate. As you see here, length and sum work fine, but mean
throws this same error whatever dataset we use.

cast(aqm, month ~ variable, length)

 month ozone solar.r wind temp
1     5    26      27   31   31
2     6     9      30   30   30
3     7    26      31   31   31
4     8    26      28   31   31
5     9    29      30   30   30

cast(aqm, month ~ variable, sum)

 month ozone solar.r  wind temp
1     5   614    4895 360.3 2032
2     6   265    5705 308.0 2373
3     7  1537    6711 277.2 2601
4     8  1559    4812 272.6 2603
5     9   912    5023 305.4 2307

cast(aqm, month ~ variable, mean)

Error in get(as.character(FUN), mode = "function", envir = envir) :
 variable "fun" of mode "function" was not found

Our environment:

version

              _
platform       i386-apple-darwin8.10.1
arch           i386
os             darwin8.10.1
system         i386, darwin8.10.1
status
major          2
minor          6.2
year           2008
month          02
day            08
svn rev        44383
language       R
version.string R version 2.6.2 (2008-02-08)

installed.packages()

reshape    "reshape"
"/Library/Frameworks/R.framework/Resources/library" "0.8.0"
NA            NA


Please, could you help use to work out this issue? Thanks!