Stacked Chart with start Datetime and duration

I'm trying to plot the a stacked bar chart with following data( goal is to have floating bar chart to show the time-line ). but unable to do that as excel requires columns to be number for stacked bar chart.

I'm using Excel 2007.

Category Start Date Duration
A-B 11/16/08 23:30 70
B-C 11/17/08 2:00 60
C-D 11/17/08 1:00 120
E-F 11/18/08 1:30 80

Please let me know if there is another alternative to show floating bar chart.

Thanks