Using Excel2007
With Rick Rothstein's code (his post dd 09/10/2008 under "Date & Time Picker
Control 6.0" I managed to get the date picker to pop up on double click and
perform nicely as expected.

Now I wanted to provide the same functionality on a different sheet in the
same workbook. So I copied the code into this sheet but now I get a 424
"Object required" when I click (single or double) in any cell on that sheet;
the debugger stops at the line which I have marked with ==.
The other sheet is still working fine.

This is the code:
'***************** START OF CODE *****************
Dim CurrentDTPickerCell As Range

Private Sub DTPicker1_CloseUp()
CurrentDTPickerCell.Value = DTPicker1.Value
DTPicker1.Visible = False
End Sub

Private Sub Worksheet_BeforeDoubleClick(ByVal Target As Range, _
Cancel As Boolean)
If Not Intersect(Target, Range("B:C")) Is Nothing Then
Cancel = True
Set CurrentDTPickerCell = Target
DTPicker1.Visible = True
DTPicker1.Top = Target.Top
DTPicker1.Left = Target.Left + Target.Width + 1
End If
End Sub

Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Target, Range("B:C")) Is Nothing Then
If DTPicker1.Visible Then DTPicker1.Visible = False
End If
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
== If DTPicker1.Visible Then DTPicker1.Visible = False
End Sub
'***************** END OF CODE *****************