External Drag&Drop problem

Hi,

Somtimes I get the following javascripterror message:

'offsetWidth' is null or not an object

It occurs at this line:

$g.style.width=($r.offsetWidth-4)+'px'

Is this a bug in DayPilot or is it my external html that is not correct? My code looks like this:

<tr onmousedown='return DayPilotCalendar.dragStart(this, 60*30, "<%# Eval("Id")%>", this.innerHTML);'
style="cursor: move;" unselectable='on'>

Also, I wonder if there is a way to call dragStart without deleting the draged item? When I try to send null instead of "this" parts of the page/html gets selected when I drag the item to the calendar.

Thanks

Andreas