Probably that time does not exist in your locale due to summer time.

You can avoid that with more careful conversion, I would assume GMT and add
an offset afterwards to correct it. Currently your code assumes whatever is
local time on your machine. It is not always easy to rectify but it is well
known.





On Tuesday, February 5, 2013, John McEvoy wrote:

> Thanks for your quick responses. There was indeed an NA value lurking in
> the Da object. Funnily enough there were no NAs in the original date
> column, only when it was converted to a POSIXct  object did it throw up and
> "NA" and then it was right in the middle of about 7000 records so i didn't
> spot it. Any suggestions as to why the "as.POSIXct" function would turn
> this one record into an NA ? It was formatted the same as all the others,
>  "2010-10-03 02:30:00".
> Thanks again.
> John
>
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Michael Sumner
Hobart, Australia
e-mail: mdsumner@gmail.com

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