Outlook Mail Delivery Fails in Excel VBA in Office 365 OPP (64bit) Environment.

Please help me with the title.

The following code, which worked properly in a 32-bit environment, will fail in a new environment:
Reference settings have been checked for Microsoft Office 16.0 Object Library.
According to the olMailItem properties, the subject is included, but there seems to be an error between To and Body.Also, if you look at the watch expression, the To and Body types are displayed as Variant/Integer.

Also, the Send method fails, but it works until Save.
The same symptom also occurred when the code was not set to reference setting.
I would appreciate it if you could let me know how to run the Send method.

error message

Runtime error '287'—Application definition or object definition error.

code

Sub S01()'Reference settings are used.

    DimolAppObjAsOutlook.Application
    DimmailObjAsOutlook.MailItem
    Dim toAddress As String

    SetolAppObj=New Outlook.Application
    SetmailObj=olAppObj.CreateItem(olMailItem) 'Type name of item to be specified =olMailItem, value = 0

    toAddress="********@*****"

    With mailObj
        .To=toAddress
        .Subject="*****"
        .Body="*****"
        .BodyFormat=olFormatHTML
    End With

    mailObj.Send

    SetolAppObj=Nothing
    Set mailObj=Nothing

End Sub