I have popup calendar in a spreadsheet that works fine until I share the file allowing other users to access simultaneously. As soon as I share the file, the VBA code breaks producing the error in the title. I'm hoping that someone has an easy fix. Here is the code for the calender:

Private Sub Calendar1_Click()
ActiveCell.Value = CDbl(Calendar1.Value)
'ActiveCell.NumberFormat = "mm/dd/yyyy"
ActiveCell.Select
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Cells.Count 1 Then Exit Sub
If (Not Application.Intersect(Range("b4:b28,f4:f28,d32,i34 "), Target) Is Nothing) Then
Calendar1.Left = Target.Left + Target.Width - Calendar1.Width
Calendar1.Top = Target.Top + Target.Height
Calendar1.Visible = True
' select Today's date in the Calendar
Calendar1.Value = Date
ElseIf Calendar1.Visible Then Calendar1.Visible = False
End If
End Sub

Thanks in advance for anyone who can assist