Tables Tabulate Grouping Columns

[#1]

I have a huge data sheet that I'm trying to simplify for easier understanding. I'm trying to group all the same dates together into one. I included two pictures of the successful before and after when I go to "Tables" -> "Tabulate" -> moves the INSPDATE to "drop zone for rows" and click on "Add Group Columns."

       

That was the successful one. However, when I tried to do the same thing to another data sheet, it would not group together all the dates. It would still look like the before pictures. Any clues of how to fix it? Any ideas? Your help will be much appreciated.

[#2]

Here's two attachment of the JMP file if you want to experiment it yourself. The one that said "success" is the one that work. The 2nd one that say "failure" is the one that doesn't work. Maybe there's a different in format between this two. Hope you can solve it.

[#3]

If you expand the format of the Date column to include the time (m/d/y h:m:s), you'll see that the time in the success dataset is all at 12:00.  But the date column in the failure dataset has many different values for time.

05/19/2013 11:54:14 PM

05/20/2013 12:09:13 AM

05/20/2013 12:13:49 AM

05/20/2013 12:18:43 AM

05/20/2013 12:29:05 AM

05/20/2013 12:47:05 AM

05/20/2013 1:46:25 AM

05/20/2013 2:05:17 AM

05/20/2013 2:11:37 AM

05/20/2013 2:17:31 AM

05/20/2013 2:19:32 AM

05/20/2013 2:22:08 AM

05/20/2013 2:25:26 AM