I can't seem to replicate this error. Can you post the exact steps to replicate this?
I don't get any error, but I notice that after I click "Press Here" one time, the value of C1WebDateEdit1 will not update when I select a different date.
To fix this I added the following between the <head> tags
<script type="text/javascript">
function Calendar_SelChange(calendar, seltype, seldates)
{
if (window.edit)
{
window.edit.set_Date(calendar.SelectedDate);
}
}
function C1WebDateEdit1_OnClientCustomButtonClick(aC1Edit)
{
window.edit = aC1Edit;
};
</script>
and set these Onclient commands
C1WebDateEdit1.OnClientCustomButtonClick = C1WebDateEdit1_OnClientCustomButtonClick
C1WebCalendar1.OnClientSelChange = Calendar_SelChange
That fixes the problem I was having with your sample.
regards,
-Greg L