Comparing two custom time fields

Hey,

I have two custom fields of type 'time of day' on an opportunity record:

1. appttime
2. apptendtime

These are used to record the time of the first appointment (a.k.a. event) for that opportunity.  I have a script that automatically creates an event from this (and other) info.

I am trying to put some validation on the form that checks that apptendtime is later in the day than appttime.  Therefore, I have used:

if (apptendtime <= appttime) {alert('apptendtime is not later than appttime')};


However, the <= operator isn't working properly.  It returns true every time!


I have tried using standard date operators (e.g. getTime()) but these don't work.  I think this is because the value in the fields are of type 'time of day' not 'date'.