Filename missing - Documents Module Suite CRM

a document is returned from an email after signing, after making entry in documents module its file name is missing.
what im missing??

$documentBean = BeanFactory::getBean('Documents')->retrieve_by_string_fields(
            'envelope_id' => $envelope_id,
    $docName = $documentBean->document_name;

    $DocRevBean = BeanFactory::newBean('DocumentRevisions');
    $DocRevBean->change_log="Document Created";
    $DocRevBean->filename = $docName.' - SignedRevFile';
    $DocRevBean->document_name = $docName.' - SignedRevDocName';
    $DocRevBean->file_ext = '.pdf';
    $DocRevBean->doc_type = "Sugar";
    $DocRevBean->revision = "1";
    $doc_revision_id = $DocRevBean->save();


    $newDocumentBean = BeanFactory::newBean('Documents');
    $newDocumentBean->lead_id = $documentBean->lead_id;
    $newDocumentBean->doc_type = $documentBean->doc_type;
    $newDocumentBean->document_revision_id = $doc_revision_id;
    $newDocumentBean->document_name = $documentBean->document_name.' - SignedDocDocName';
    $newDocumentBean->filename= $documentBean->document_name.' - SignedDocFile';

    $new_doc_id = $newDocumentBean->save();
        $doc_rev_bean = BeanFactory::getBean('DocumentRevisions', $doc_revision_id);
        $doc_rev_bean->document_id = $new_doc_id;

Have a look at this

and see how it looks in the database. Maybe you will be able to understand.

Pay attention to this part

Where, in SuiteCRM, do you see the missing filename? Is it from Emails module, or somewhere else?