how to check the missing log

i got a list which contain the date and time for my windows logging.
each interval time is approx 3mins.
after i manually calculate,found that in 24hrs ,certain time, the windows failed to log.
how to find the missing log?
it got thounsands over logs,which i can't check it one by one.
can i just with a formula and find the log?

example of my log:
17/08/2007 05:13:55
17/08/2007 05:16:34
17/08/2007 05:19:14
17/08/2007 05:21:54
17/08/2007 05:24:34
17/08/2007 05:27:14
17/08/2007 05:29:55
17/08/2007 05:32:34
17/08/2007 05:35:14
17/08/2007 05:37:54
17/08/2007 05:40:34
17/08/2007 05:43:14
17/08/2007 05:45:54
17/08/2007 05:48:34
17/08/2007 05:51:14
17/08/2007 05:53:54
17/08/2007 05:56:34
17/08/2007 05:59:14

Hi there,

If your list of times begins in cell A1 then enter the following formula in cell B1 & copy it all the way down beside the list:

=IF(A2 - A1 > TIMEVALUE("0:04"),  "Log Missing",  "")

This produces a "Log Missing" message immediately above any cell whose log time is more than four minutes behind the cell above it. To use a different time interval just change TIMEVALUE("0:04") to suit.

You can also enter the following formula (anywhere) to show you the number of the logs that are missing:

="Missing Logs = "  &  COUNTA(B1:B99999,  "Log Missing")

Hope this helps,

Greg M

the second formula is incorrect.
only one log is missing,but it display 2 logs.

Hi Lonely,

Would you post me a copy of your workbook so I can take a look at it?

Thanks,

Greg M

Hi again,

Sorry - try this:

="Missing Logs = "  &  COUNTIF(B1:B18,"Log Missing")

I tried it on an example which HAD two missing logs, so the formula appeared to work correctly. Hope this one's OK for you.

Regards,

Greg M

the 1st formula always display 2 logs, but actually only one is missing.
the second formula always return 0, actual one missing log.