Importing commission junctions vouchers

Question

I am trying to import data from commission junction to my database in MySQL. I succeeded to import the advertisers, but I still fail in importing the vouchers. The parameters who are making a problem are "postingDate", "promotion-end-date" and "promotion-start-date".

public function import()
{
    $get_url = $this->get_response_by_url_voucher();

    $xml = new SimpleXMLElement($get_url);
    $json_string = json_encode($xml);    
    $getvoucher = json_decode($json_string, TRUE);
    $this->import_voucher($getvoucher);
}   

public function import_voucher($getvoucher = [])
{
    if($getvoucher) 
    {
        foreach($getvoucher['links']['link'] as $voucher)
        {   
            $attr = [
                'link-id'              => $voucher['link-id'],
                'advertiser-id'        => $voucher['advertiser-id'],
                'description'          => $voucher['description'],
                'coupon-code'          => $voucher['coupon-code'],
                'link-name'            => $voucher['link-name'],
                'promotion-type'       => $voucher['promotion-type'],
                'clickUrl'             => $voucher['clickUrl'],
                'promotion-start-date'   => $voucher['promotion-start-date'],
                'promotion-end-date'   => $voucher['promotion-end-date'],
                'relationship-status'  => (int)$voucher['relationship-status'],
                'language'             => $voucher['language'],  
            ];

            $this->db->replace($this->table_voucher_name, $attr);
        }
    }
}

If I echo one of this three parameters I should get the dates for each voucher, but instead I get something like this:

ArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArray2018-04-16 19:47:00.0ArrayArrayArrayArrayArrayArray2018-04-22 16:00:00.02018-04-22 15:00:00.0Array2018-04-22 09:00:00.0ArrayArray2018-04-22 15:00:00.0ArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArrayArray

Only some of the vouchers have dates, so there are only a few I can import this way to my database. What is wrong here?