Auto Running Number In Worksheet

I have a PO Template, which I use it to issue Purchase Order and keep track on monthly purchases.

This PO template allow me generate a fresh PO with feature of auto "Name" which is the running number for the PO.

However, i have a problem to generate the reference number in the sequence which tirelessly seach a way to work this out.

Below is my current code, as i tried to set my statting code say "87500", the next incremental number just dont generate according to it sequence..

Code:
Sub AddSheet()
Dim strName As String
Dim intNum As Integer, intLastNum As Integer
Dim wsh As Worksheet
Dim lngRow
For Each wsh In Worksheets

[Code]....