VBA code has disabled my paste option

I have a VBA code that enables a pop-up calendar for a couple of cells but it seems that it has disabled my paste function completely. I need it back. Please help. Here is the code I have:

Private Sub Calendar1_Click()
ActiveCell.Value = Calendar1.Value
End Sub

Private Sub Calendar2_Click()
ActiveCell.Value = Calendar2.Value
End Sub

Private Sub Calendar3_Click()
ActiveCell.Value = Calendar3.Value
End Sub

Private Sub Calendar4_Click()
ActiveCell.Value = Calendar4.Value
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If ActiveCell.Address = "$K$2" Then
Calendar1.Visible = True
Else
Calendar1.Visible = False
End If
If ActiveCell.Address = "$C$8" Then
Calendar2.Visible = True
Else
Calendar2.Visible = False
End If
If ActiveCell.Address = "$I$8" Then
Calendar3.Visible = True
Else
Calendar3.Visible = False
End If
If ActiveCell.Address = "$A$4" Then
Calendar4.Visible = True
Else
Calendar4.Visible = False
End If
End Sub