Try putting a T between the date and time portion.
startDateEB << Set Format( Format( "yyyy-mm-ddThh:mm:ss" ) );
From the Numeric Formats section of the help page for the Column Info dialog box (text edit boxes use the same formats):
Time Formats
When you choose a Time format, you can also specify an Input Format. The Time format indicates how the time appears in the data table cells, and the Input Format indicates how you enter the time.
• You can add the number of hours, minutes, and seconds after midnight of the prepended date for the following date formats:
– m/d/y
– d/m/y
– y/m/d
– ddMonyyyy
– Monddyyyy
– Locale Date
For example, December 31, 2004 has a numeric value of 3,187,296,600, which represents 12/31/2004 12:10 AM.
• :day:hr:m and :day:hr:m:s show the number of days, hours, minutes, and seconds since January 1, 1904. For example, the results for December 31, 2004 are :36890:00:10: and :36890:00:10:00.
• h:m:s and h:m show the hours, minutes, and seconds portion of the date in the date field. For example, the results for December 31, 2004 at 12:10 AM are 12:10:00 AM and 12:10 AM.
• yyyy-mm-ddThh:mm and yyyy-mm-ddThh:mm:ss show the year, month, day, and time. For example, 2004-12-31T12:10:00. T is a literal value, representing itself.