Difficulty with calculated column

[nmss18]

Hello,
I have a column with date & time data in this format:
2012-02-01 00:12:05.637
I need to separate the date from the time, and for the time, I just need the hours,minutes,seconds. Sor using the example above, I want to create a calculated column with the time data to look like this:
00:12:05

Any assiatance would be appreciated.
Thanks,
Nathan
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[masplin]

Silly question but is the length 23 for every entry? You only need one to be differnet and you get an error on the whole column. Just click the table heading to filter and see if only one value. I've had similar issues and found one entry was rogue. I think when this happens the error box shows #Error and also "show first error" or similar wording which also indicates its not a formaula error but an input data error and will take you to the first offending field.

Mike