Excel not recognizing dates as dates

[Guest]

I have a column of dates that were entered by another program. The values
that end in "06", for example, Excel is not recognizing them as dates, and
subsequently when I try to change the format to "dd/mm/yyyy", it does not
correct these cells. I have both formaically and manually changed the years
to a 4 digit year (31/01/06 --> 31/01/2006), but Excel still does not
recognize it as a date. (if I enter a 1*c1 and copy the formula down beside
the date column, some values result in VALUE! and some result in the 39367
range). how can I get all dates to be recognized?

Ex:
31/01/06 not recognized as a date, even if i manually change to /2006
05/10/2007 recognized as a date
04/01/2007 recognized as a date
04/01/2007 recognized as a date
11/06/2006 recognized as a date
18/07/05 not recognized as a date, even if i manually change to /2005
03/01/2006 recognized as a date
30/08/06 not recognized as a date, even if i manually change to /2006
13/10/06 not recognized as a date, even if i manually change to /2006

Thank you very much.

 

[Guest]

Try Data > Text to Columns ?
Select only the col of "dates", click Data > Text to Columns. Click Next >
Next. In step 3 of the wizard, check "Date" under Col data format, then
choose: DMY from the droplist. Click Finish.