CalendarExtender on ModalPopupExtender

[Rahul]

I have a web application in ASP.NET (in VS2008). We have used
CalendarExtender Ajax control in a couple of pages in the application and it
works fine.

However, if the calendarextendar is situated on a modalpopup, the area where
the calendar should appear shows the area below the modalpopup! That is, the
area where the calendar should come up appears to be transparent (upto the
level below the modalpopup).

Please note that this happens only in Internet Explorer 6, not in IE7 or
Firefox.

Looking forward to your help!

Regards.