SUMPRODUCT returning FALSE

[Aflatoon]

I'm not sure why you are using SUMPRODUCT rather than SUMIF, but you could use:

Sub SumCharges()
Dim ws As Worksheet
Dim LastRow As Long
Dim ws1 As Worksheet
Dim LastRow1 As Long
Dim tAmount As Range
Dim R As Long   'Used for Rows
Dim sFormula As String
Set ws = ThisWorkbook.Worksheets("Vehicle Listing")
LastRow = ws.Range("A65536").End(xlUp).Row
Set ws1 = ThisWorkbook.Worksheets("Event Repair - OK")
LastRow1 = ws1.Range("A65536").End(xlUp).Row
Set tAmount = ws.Range("P2:P" & LastRow)
For R = 2 To LastRow   'Used for populating Rows
    If Cells(R, 1).Value <> "" Then
        sFormula = "sumproduct((A2:A" & LastRow & "=A2)*P2:P" & LastRow & ")"
        Cells(R, 4).Value = ws.Evaluate(sFormula)
    End If
Next R
End Sub