DHL apparently only supports creating 1 label at a time.

Author: fdeschenes

lib/dhl/ecommerce/label.rb

@@ -202,7 +202,9 @@ def self.create_in_batches(attributes)
             url = "https://api.dhlglobalmail.com/v1/#{self.resource_name.downcase}/US/#{location_id}/zpl"
           end
 
-          location_attributes.each_slice(500).collect do |slice|
+          # DHL e-Commerce's documentation says they support creating 500 labels
+          # at once but as it turns out, they don't.
+          location_attributes.each_slice(1).collect do |slice|
             labels = slice.map do |slice_attributes|
               new slice_attributes
             end

lib/dhl/ecommerce/version.rb

@@ -1,5 +1,5 @@
 module DHL
   module Ecommerce
-    VERSION = "1.0"
+    VERSION = "1.0.1"
   end
 end