Public Type Appointment
    RefNos() As String * 10
    TimeSlot As Integer
    AvailableTellers As Integer
End Type

Public Type AppointmentDay
    Appointments() As Appointment
End Type

Option Explicit

Public Name As String
Private QueueTellerCount As Integer 'set to 1 for regular queue, else set to n for bank style queue
Private SlotLength As Integer 'how long each slot is in minutes
Private SlotsPerDay As Integer 'how many slots per day
Private Days() As AppointmentDay 'array of slots for each day, containing ref no's.
Private DateStart As String 'format 2009/01/28
Public TimeStart As String 'format 01:46:11 PM
Private NextSlot As Integer 'for ref numbers without cellphone

Implements IPropertyBagClass

..........

Private Sub IPropertyBagClass_WriteProperties(PropBag As PropertyBagClass)
Dim i As Integer

    PropBag.WriteProperty "Name", Name
    PropBag.WriteProperty "QueueTellerCount", QueueTellerCount
    PropBag.WriteProperty "SlotLength", SlotLength
    PropBag.WriteProperty "SlotsPerDay", SlotsPerDay
    PropBag.WriteProperty "UboundDays", UBound(Days)
    For i = 0 To UBound(Days)
        PropBag.WriteProperty "Days" & i, Days(i) 'ERROR OVER HERE
    Next
    PropBag.WriteProperty "DateStart", DateStart
    PropBag.WriteProperty "TimeStart", TimeStart
    PropBag.WriteProperty "NextSlot", NextSlot

End Sub

Public Sub WriteProperty(Name As String, Value As Variant, Optional DefaultValue As Variant) 'Changing this to Friend made no difference

   Dim p As PropertyBagClass
   Dim i As IPropertyBagClass

   If TypeOf Value Is IPropertyBagClass Then
      Set p = New PropertyBagClass
     
      Set i = Value
      i.WriteProperties p
      Set i = Nothing
     
      pb.WriteProperty Name, p.Contents
      Set p = Nothing
   Else
      pb.WriteProperty Name, Value, DefaultValue
   End If
   
End Sub