as an alternative.
why not group by the employee, make a group for the Date (ignore the time).suppress the details, and display the header and footer record, which would be the earliest and latest for a date respectively.
if this doesn't quite fit the bill, you could set a shared variable in the group header (start time), then in the footer you could compute the time using DATEDIFF between the start time from the header and the end time from the footer...you would probably want to suppress the group header (start time) as well.
HTH