Runtime Error 424 - Object Required

Hey guys & gals.. I am getting a runtime error 424: Object required on the line "For Each ws In memberLists.Worksheet"

The entire code is below. How can I fix this?

Dim memberLists As Workbook
Dim chapterColumn As String

Sub ParseInputToWorksheets()

    Set memberLists = ActiveWorkbook
    chapterColumn = "E"
    
    Dim newMembers As Workbook
    Dim newMembersFilePath As String
    newMembersFilePath = "C:\...\NewMembers.xls"
    Set newMembers = GetObject(newMembersFilePath)
    
    Dim r As Range
    For Each r In newMembers.Worksheets(1).Rows
        Dim chapterName As String
        chapterName = r.Cells(1, chapterColumn)
        Call CopyToChapter(chapterName, r)
    Next
    
End Sub

Private Sub CopyToChapter(chapterName As String, r As Range)
    Dim ws As Worksheet
    For Each ws In memberLists.Worksheets
        If ws.Name = chapterName Then
            Dim iRow As Long
                iRow = FirstEmptyRowIndex(ws)
                r.Copy (ws.Rows(iRow))
            Exit Sub
        End If
    Next
End Sub



Private Function FirstEmptyRowIndex(ws As Worksheet) As Long
    Dim firstCell As Range
    Set firstCell = ws.Range("A1")
    Dim iRow As Long
    iRow = 0
    Do
        iRow = iRow + 1
        If firstCell.Offset(iRow, 0).Value = "" Then Exit Do
    Loop
    FirstEmptyRowIndex = iRow + 1
End Function