Action TCPDF : attach file to email with customize file name

Hi,
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sorry I make a new post because I've already mark the previous ad solved, but it is not.
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I've used TCPDF action, with a customized file name:
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<?php$form->data['pdf_file_name'] = 'Preventivo_IX_per'.'_'.$form->data['name'].'_'.date("Y-m-d_h:i:s");?>

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What should I put in the attachment field in the email action?
I cannot make it works.
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Thanks!

Here fields avalaible from debugger:
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​[pre] [button-configuratore] => Calcola
[pdf_file_name] => Preventivo_IX_per_Miriam Monza_2018-08-27_06:49:09
[preventivo] => Preventivo_IX_per_Miriam Monza_2018-08-27_06:49:09.pdf
[pdf_link] => https://www.arxivar.it/components/com_chronoforms5/chronoforms/pdfs/config-IX-v5-fork1aggior13conARXFE/Preventivo_IX_per_Miriam Monza_2018-08-27_06:49:09.pdf
[pdf_link2] => <a href='https://www.arxivar.it/components/com_chronoforms5/chronoforms/pdfs/config-IX-v5-fork1aggior13conARXFE/Preventivo_IX_per_Miriam Monza_2018-08-27_06:49:09.pdf' >scarica</a>[br] [br])[br][/pre]

Array
(
    [preventivo] => Array
        (
            [name] => Preventivo_IX_per_Miriam Monza_2018-08-27_06:49:09.pdf
            [path] => /home/arxivar.it/public_html/components/com_chronoforms5/chronoforms/pdfs/config-IX-v5-fork1aggior13conARXFE/Preventivo_IX_per_Miriam Monza_2018-08-27_06:49:09.pdf
            [size] => 0[br]            [link] => /home/arxivar.it/public_html/components/com_chronoforms5/chronoforms/pdfs/config-IX-v5-fork1aggior13conARXFE/Preventivo_IX_per_Miriam Monza_2018-08-27_06:49:09.pdf[br]        )[br][br])