Replace Cells Between Range

I have a list that looks like the list on my sample file. You will see ME28A16 at the top and the bottom of the list. I want to fill the Cells inbetween with that value. In my real file It may start ME or it may start PE

Here is the Script that I am using but I can not get it to work:



Dim CurrentRow As Long
Dim LastRow As Long
Dim CurrentText

LastRow = Range("A65000").End(xlUp).Row

For CurrentRow = 1 To LastRow
If InStr(4, Cells(CurrentRow, 4).Value, "M", vbTextCompare) > 0 Or _
InStr(4, Cells(CurrentRow, 4).Value, "P", vbTextCompare) > 0 Then
CurrentText = Cells(CurrentRow, 4).Value
Else
Cells(CurrentRow, 4).Value = CurrentText
End If
Next CurrentRow