R code not working under R version 2.13 for Mac

Thanks Jeff,

I have extracted the first 50 lines of the d4 data.frame and put them
into the attached d4a.RData file. In case the list handler does not
allow attachments I have uploaded a copy of the file onto my web site
and it can be downloaded from: http://www.lucameyer.com/d4a.RData

Please notice that what I am trying to do is to aggregate over
d4a$progetto and get a sum of d4a$ore. The error I get states:

Error in units == units[1L] : comparison between these types has not
been implemented

Can you or anyone on the list spot what the matter could be for me? 

Thanks,
Luca

Il giorno 09/lug/2011, alle ore 18.02, Jeffrey Ryan ha scritto:

If you can provide a reproducible example, i.e. a *small* subset of
your data.frame that illustrates the error - as it would allow those
on the list to attempt to replicate.  

"some info" can't be sourced in.  Try 'dput' and paste the results.

Jeff

On Sat, Jul 9, 2011 at 10:31 AM, Luca Meyer <lucam1968 at gmail.com
<mailto:lucam1968 at gmail.com>> wrote:

    Hello,

    I had a piece of code regularly working on R 2.12 now giving error
    on the newly installed R 2.13:

    d5 <- aggregate(d4[,c("ore")],list(d4$progetto),sum)

    Errore in units == units[1L] : confronto tra questi tipi non
    implementato - that's basically saying "comparison between these
    types has not been implemented"

    How can I solve this issue? Please find attached some info about
    data frame d4

    > class(d4)

    [1] "data.frame"

    > names(d4)

    [1] "data"      "anno"      "mese"      "settimana" "progetto"  "ore"

    > class(d4$ore)

    [1] "difftime"

    > class(d4$progetto)

    [1] "factor"

    Also, this is the R version I have installed:

    R version 2.13.0 (2011-04-13)
    Copyright (C) 2011 The R Foundation for Statistical Computing
    ISBN 3-900051-07-0
    Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)

    Thanks,
    Luca