This is the code I'm working with. There are no errors but something goes wrong with the copying and I have no idea what.

Code:
Sub MergeWorkbooks ()
    Dim choice As Integer, rng As Range
    Dim lrw As Long
    Dim lcol As Integer
    
    ' Case 1 = last row
    ' Case 2 = last column
    ' Case 3 = last cell

    Select Case choice

    Case 1:
        On Error Resume Next
        RDB_Last = rng.Find(What:="*", _
                            after:=rng.Cells(1), _
                            Lookat:=xlPart, _
                            LookIn:=xlFormulas, _
                            SearchOrder:=xlByRows, _
                            SearchDirection:=xlPrevious, _
                            MatchCase:=False).Row
        On Error GoTo 0

    Case 2:
        On Error Resume Next
        RDB_Last = rng.Find(What:="*", _
                            after:=rng.Cells(1), _
                            Lookat:=xlPart, _
                            LookIn:=xlFormulas, _
                            SearchOrder:=xlByColumns, _
                            SearchDirection:=xlPrevious, _
                            MatchCase:=False).Column
        On Error GoTo 0

    Case 3:
        On Error Resume Next
        lrw = rng.Find(What:="*", _
                       after:=rng.Cells(1), _
                       Lookat:=xlPart, _
                       LookIn:=xlFormulas, _
                       SearchOrder:=xlByRows, _
                       SearchDirection:=xlPrevious, _
                       MatchCase:=False).Row
        On Error GoTo 0

        On Error Resume Next
        lcol = rng.Find(What:="*", _
                        after:=rng.Cells(1), _
                        Lookat:=xlPart, _
                        LookIn:=xlFormulas, _
                        SearchOrder:=xlByColumns, _
                        SearchDirection:=xlPrevious, _
                        MatchCase:=False).Column
        On Error GoTo 0

        On Error Resume Next
        RDB_Last = rng.Parent.Cells(lrw, lcol).Address(False, False)
        If Err.Number > 0 Then
            RDB_Last = rng.Cells(1).Address(False, False)
            Err.Clear
        End If
        On Error GoTo 0

    End Select

    
    
    ' MERGE LISTS
    ' --------------------------------------------------------------
    
    
    Dim MyPath As String, FilesInPath As String
    Dim MyFiles() As String
    Dim SourceRcount As Long, Fnum As Long
    Dim mybook As Workbook, BaseWks As Worksheet
    Dim sourceRange As Range, destrange As Range
    Dim rnum As Long, CalcMode As Long
    Dim FirstCell As String

    'Fill in the path\folder where the files are
    MyPath = "C:\xyz\Project lists"

    'Add a slash at the end if the user forget it
    If Right(MyPath, 1) <> "\" Then
        MyPath = MyPath & "\"
    End If

    'If there are no Excel files in the folder exit the sub
    FilesInPath = Dir(MyPath & "*.xls*")
    If FilesInPath = "" Then
        MsgBox "No files found"
        Exit Sub
    End If

    'Fill the array(myFiles)with the list of Excel files in the folder
    Fnum = 0
    Do While FilesInPath <> ""
        Fnum = Fnum + 1
        ReDim Preserve MyFiles(1 To Fnum)
        MyFiles(Fnum) = FilesInPath
        FilesInPath = Dir()
    Loop

    'Change ScreenUpdating, Calculation and EnableEvents
    With Application
        CalcMode = .Calculation
        .Calculation = xlCalculationManual
        .ScreenUpdating = False
        .EnableEvents = False
    End With

    'Add a new workbook with one sheet
    Set BaseWks = Workbooks.Add(xlWBATWorksheet).Worksheets(1)
    rnum = 1
    ActiveWorkbook.SaveAs "C:\xyz\MasterProjectList.xlsx"
    
    ' Set header
    Cells(1, 1).Value = "Project Number"
    Cells(1, 2).Value = "Project Description 1"
    Cells(1, 3).Value = "Project Description 2"
    Cells(1, 4).Value = "Project Description 3"
    Cells(1, 5).Value = "Project Description 4"
    Cells(1, 6).Value = "Priority Status"
    Cells(1, 7).Value = "Process approval status"
    Cells(1, 8).Value = "Project Manager"
    Cells(1, 9).Value = "Planning responsible"
    Cells(1, 10).Value = "Customer"
    Cells(1, 11).Value = "Profit Center"
 

    'Loop through all files in the array(myFiles)
    If Fnum > 0 Then
        For Fnum = LBound(MyFiles) To UBound(MyFiles)
            Set mybook = Nothing
            On Error Resume Next
            Set mybook = Workbooks.Open(MyPath & MyFiles(Fnum))
            On Error GoTo 0

            If Not mybook Is Nothing Then

                On Error Resume Next

        With mybook.Worksheets("SpecificList")
                    FirstCell = "A1"
                Set sourceRange = .Range(FirstCell & ":" & RDB_Last(3, .Cells))
                'Test if the row of the last cell >= then the row of the FirstCell
                If RDB_Last(1, .Cells) < .Range(FirstCell).Row Then
                Set sourceRange = Nothing
            End If
        End With

                If Err.Number > 0 Then
                    Err.Clear
                    Set sourceRange = Nothing
                Else
                    'if SourceRange use all columns then skip this file
                    If sourceRange.Columns.Count >= BaseWks.Columns.Count Then
                        Set sourceRange = Nothing
                    End If
                End If
                On Error GoTo 0

                If Not sourceRange Is Nothing Then

                    SourceRcount = sourceRange.Rows.Count

                    If rnum + SourceRcount >= BaseWks.Rows.Count Then
                        MsgBox "Sorry there are not enough rows in the sheet"
                        BaseWks.Columns.AutoFit
                        mybook.Close savechanges:=False
                        GoTo ExitTheSub
                    Else

                        'Set the destrange
                        Set destrange = BaseWks.Range("B" & rnum)

                        'we copy the values from the sourceRange to the destrange
                        With sourceRange
                            Set destrange = destrange. _
                                            Resize(.Rows.Count, .Columns.Count)
                        End With
                        destrange.Value = sourceRange.Value

                        rnum = rnum + SourceRcount
                    End If
                End If
                mybook.Close savechanges:=False
            End If

        Next Fnum
        BaseWks.Columns.AutoFit
    End If

ExitTheSub:
    'Restore ScreenUpdating, Calculation and EnableEvents
    With Application
        .ScreenUpdating = True
        .EnableEvents = True
        .Calculation = CalcMode
    End With
End Sub
Any ideas guys?

Cheers!