Scatter Plot Min/Max Values in Numbers not Date

From http://office.microsoft.com/en-us/ex...240.aspx?CTT=1

Microsoft Excel stores dates as sequential numbers that are called serial values. For example, in Microsoft Excel for Windows, January 1, 1900 is serial number 1, and January 1, 2008 is serial number 39448 because it is 39,448 days after January 1, 1900. Excel stores times as decimal fractions because time is considered a portion of a day. The decimal number is a value ranging from 0 (zero) to 0.99999999, representing the times from 0:00:00 (12:00:00 A.M.) to 23:59:59 (11:59:59 P.M.).

Because dates and times are values, they can be added, subtracted, and included in other calculations. You can view a date as a serial value and a time as a decimal fraction by changing the format of the cell that contains the date or time to General format.

So the values you are seeing in minimum and maximum fields are these date/time serial numbers. I don't work with date/time serials very much, but I expect if you figure out what serial numbers correspond to your desired max and min values, you can enter those values into the max and min fields to get what you are after.