Microsoft VBA Error - Run time Error - 1004 - excel

Question

Run-time error '1004': The PivotTable field name is not valid. To create a PivotTable report you must use data that is organized as a list of labeled columns. If you are changing the name of a PivotTable field, you must type a new name for the field.
Here Is my Code?
Please tell me the mistake so I can understand it. also How Can I Correct it?
Option Explicit
Public PageName, RowName, ColumnName, DataName As String
Sub ShowForms()
frmGenerateReports.Show
End Sub
Sub CreatePivot()
Dim Destination, RangeData As Range
Set Destination = Worksheets("Reports").Range("A1")
Set RangeData = Range("A1", Range("I1").End(xlDown))
ActiveWorkbook.PivotCaches.Create _
(SourceType:=xlDatabase, SourceData:=RangeData) _
.CreatePivotTable TableDestination:=Destination, TableName:="SalesPivot"
End Sub
Sub SetFields()
Dim PvtTable As PivotTable
Set PvtTable = Worksheets("Reports").PivotTables("SalesPivot")
With PvtTable
.PivotFields(PageName).Orientation = xlPageField
.PivotFields(RowName).Orientation = xlRowField
.PivotFields(ColumnName).Orientation = xlColumnField
.PivotFields(DataName).Orientation = xlDataField
End With
ActiveWorkbook.Sheets("Reports").Activate
If frmGenerateReports.Sales <> "Model" Then
PvtTable.PivotSelect "", xlDataOnly
Selection.NumberFormat = "$#, ##0"
End If
Range("E1").Select
End Sub
Sub ConsolidateData(ThisMonth)
Dim BeenThere As Boolean
Dim Compare As String
Dim Sheet As Worksheet
BeenThere = False
Sheets.Add
ActiveSheet.Name = "Reports"
If frmGenerateReports.Period = "Month" Then
Select Case ThisMonth
Case "Jan"
ThisMonth = 1
Case "Feb"
ThisMonth = 2
Case "Mar"
ThisMonth = 3
Case "Apr"
ThisMonth = 4
Case "May"
ThisMonth = 5
Case "Jun"
ThisMonth = 6
Case "Jul"
ThisMonth = 7
Case "Aug"
ThisMonth = 8
Case "Sep"
ThisMonth = 9
Case "Oct"
ThisMonth = 10
Case "Nov"
ThisMonth = 11
Case "Dec"
ThisMonth = 12
End Select
End If
Select Case frmGenerateReports.Period
Case "Month"
For Each Sheet In Worksheets
Sheet.Select
Compare = ActiveSheet.Name
On Error Resume Next
Compare = Month(CDate(Compare))
If Compare = ThisMonth Then
frmGenerateReports.StartDate = Sheet.Name
If BeenThere = False Then
GrabCells 1
BeenThere = True
Else
GrabCells 2
DoEvents
End If
End If
Next
Case "All"
GrabCells 1
Do
frmGenerateReports.StartDate = frmGenerateReports.StartDate + 1
GrabCells 2
DoEvents
Loop Until frmGenerateReports.StartDate = frmGenerateReports.EndDate
Columns("A:J").EntireColumn.AutoFit
Range("A1").Select
Case "Other"
GrabCells 1
Do
frmGenerateReports.StartDate = frmGenerateReports.StartDate + 1
GrabCells 2
DoEvents
Loop Until frmGenerateReports.StartDate = frmGenerateReports.EndDate
Columns("A:J").EntireColumn.AutoFit
Range("A1").Select
End Select
End Sub
Sub GrabCells(StartingCell)
Dim CallDate, Where, Where2 As String
CallDate = Format(frmGenerateReports.StartDate, "d-mmm-yy")
Sheets(CallDate).Select
If Range("A2").Value <> Empty Then
Where = "B" & StartingCell
Where2 = "J" & StartingCell
Range(Where, Range(Where2).End(xlDown)).Select
Application.CutCopyMode = False
Selection.Copy
Range("A1").Select
Sheets("Reports").Select
ActiveSheet.Paste
Range("A1").End(xlDown).Offset(1).Select
Else
If StartingCell = 1 Then
Application.CutCopyMode = False
Range("B1:J1").Select
Selection.Copy
Sheets("Reports").Select
ActiveSheet.Paste
Range("A2").Select
End If
End If
End Sub
Sub FinishReport()
Dim Sheet As Worksheet
Workbooks.Open Filename:=ThisWorkbook.Path & "\Reports.xlsx"
For Each Sheet In Worksheets
Sheet.Select
Cells.Select
Selection.Clear
Range("A1").Select
Next
Workbooks("Sales - Fiscal Year1.xlsm").Activate
Sheets("Reports").Select
Cells.Select
Selection.Copy
Workbooks("Reports.xlsx").Activate
ActiveSheet.Paste
Range("A1").Select
Windows("Sales - Fiscal Year1.xlsm").Activate
Application.CutCopyMode = False
ActiveWindow.SelectedSheets.Delete
Workbooks("Reports.xlsx").Activate
CreatePivot
SetFields
End Sub
I need to understand the logic behind the solution and why it caused?
So that I can prevent it from happening next time.