[R] as.Date with characters error

[Liz Hare]

Hello,

I'm trying to convert dates in the format dd-mmm-yy using as.Date.
I have two columns like this, and it works on one but not on the other.

 > options(stringsAsFactors=FALSE)
 > ortho <- read.csv("test1.csv", header=TRUE, nrows=10)
 > ortho
    DogID BirthDate xray.date
1  11877 23-Aug-87 15-Feb-88
2  11877 23-Aug-87 15-Feb-88
3   3599 21-Feb-87 21-Feb-88
4   3599 21-Feb-87 21-Feb-88
5   3599 21-Feb-87 21-Feb-88
6   3599 21-Feb-87 21-Feb-88
7   3599 21-Feb-87 21-Feb-88
8   9563 29-Jun-87 29-Jun-88
9   9563 29-Jun-87 29-Jun-88
10  9563 29-Jun-87 29-Jun-88
 > ortho$bdat <- as.Date(ortho$BirthDate, format="%d-%b-%y")
 > ortho$bdat
  [1] "1987-08-23" "1987-08-23" "1987-02-21" "1987-02-21" "1987-02-21"
  [6] "1987-02-21" "1987-02-21" "1987-06-29" "1987-06-29" "1987-06-29"
 > ortho$test.dat <- as.Date(ortho$xray.date, formate="%d-%b-%y")
Error in charToDate(x) :
   character string is not in a standard unambiguous format
 > sessionInfo()
R version 3.0.1 (2013-05-16)
Platform: x86_64-w64-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252

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

Does anyone have a guess about what's going on? I've googled for this 
error but haven't found any where the problem is with this type of 
conversion.

Thanks,
Liz

-- 
Liz Hare PhD
Dog Genetics LLC
doggene at earthlink.net
http://www.doggenetics.com