Runtime error "5852"

Question

I used this code to generate a direct mail and separate the files.

But the following mistake is being made:

Runtime error "5852" The requested object is not available.

Use of office 365

---

Sub SalvarComoDOCIndividual()
    Dim a As Integer
    Dim registro As Integer
    Dim nomeArquivo As String

    'Define o primeiro registro da mala direta
    ActiveDocument.MailMerge.DataSource.ActiveRecord = wdFirstRecord

    'Contador de registros
    a = ActiveDocument.MailMerge.DataSource.RecordCount

    'Salva todos os registros
    For registro = 1 To a
        'Atribui o valor de cada registro da coluna nome para a variável nomeArquivo que dará nome ao novo arquivo. Caso queira outro nome, basta colocar o nome da coluna desejada
        nomeArquivo = ActiveDocument.MailMerge.DataSource.DataFields("ALUNO").Value
        ActiveDocument.SaveAs2 FileName:= _
            "C:\Users\usuario\arquivos\" & nomeArquivo & ".docx", FileFormat:= _
        wdFormatXMLDocument, LockComments:=False, Password:="", AddToRecentFiles _
        :=True, WritePassword:="", ReadOnlyRecommended:=False, EmbedTrueTypeFonts _
        :=False, SaveNativePictureFormat:=False, SaveFormsData:=False, _
        SaveAsAOCELetter:=False, CompatibilityMode:=15
        ActiveDocument.MailMerge.DataSource.ActiveRecord = wdNextRecord
        Next registro
    End
End Sub