Trying to add my own functio to the plugin?

Hello,

I am trying to include a function which runs ok in my-theme/functions.php. But when i copy the function in mail.class.php (this is where i need the function) it doesn’t work anymore?

I have added these 2 functions in mail.class.php after modify_mail_operation() and i alter modify_mail_operation() a bit by
$attachments = self::render_tickets();

to test with but i doesn’t work. The pdf isn’t generated it looks like generate_pdf doesn’t work. If however i call eticket.class.php from another file it works as expected.

any pointers, tips?

static function render_tickets(){
			/**
			* some dummy static data to test with, should be the purchase data
			*/
            $data['ticket-name'] = 'Nike';
 			$data['ticket-address'] = 'beaverton';

            $pdf_filename = self::generate_pdf($data);
            //store a copy in a seperate folder
            copy(WP_CONTENT_DIR .'/uploads/tickets-tmp/'.$pdf_filename, WP_CONTENT_DIR .'/uploads/tickets/'.$pdf_filename);
            return $pdf_filename;
        }

		 static function generate_pdf($data) {
        //using xampp so set root
        $docRoot = $_SERVER["DOCUMENT_ROOT"] . '/mydomain.com';
        //temp store the pdf
        if(!defined('COUPON_UPLOAD_PATH')) {
        define ('COUPON_UPLOAD_PATH',$docRoot.'/site/wp-content/uploads/tickets-tmp');
        }
        // Include the main TCPDF library (search for installation path).
        require_once( $docRoot . '/tcpdf_min/config/lang/en.php' );
        require_once( $docRoot . '/tcpdf_min/tcpdf.php' );
        require_once( $docRoot . '/tcpdf_min/tcpdf_barcodes_2d.php' );
        // include 1D barcode class (search for installation path)
        require_once( $docRoot . '/tcpdf_min/tcpdf_barcodes_1d.php');

        require_once('eticket.class.php');

        $pdf = new FACTUURETICKET2014($data, 'P', 'mm', 'A4');
		// set document information
        $pdf->SetCreator(PDF_CREATOR);
		//etc more tcpdf specific details
        if ($data['num-of-tickets'] > 1) {
            //aanvrager
            $pdf->make_eticket($data);

        } 

        # Output the PDF document. F to save I inline
        $pdf->Output('/site/wp-content/uploads/tickets-tmp/eticket-' . $data['ticket-barcode'] . '.pdf', 'F');
    }

Anyone some tips?

http://wordpress.org/plugins/wp-e-commerce-style-email/