[edit] sign header

src/Handles/BvBeJHandle.php

@@ -120,7 +120,7 @@ class BvBeJHandle
                 RequestOptions::FORM_PARAMS => $form,
                 RequestOptions::HEADERS => [
                     'Signature' => $signature,
-                    'Signature-Date' => date($this::DATE_FORMAT, $timestamp),
+                    'Signature-Datetime' => date($this::DATE_FORMAT, $timestamp),
                     'Product-ID' => $productID
                 ]
             ]);