title: Magento add tier price programmatically but with custom fields
body: <p>I have a problem about add product tier price by code. I did some research that there is a magento API that could be used to add tier price. However, since I have customized our magento and add a new field to the tier price, which is "production time", I don't know how to add tier price via API anymore.</p>
  
  <p>Here is the sample code</p>
  
  <pre><code>$proxy = new SoapClient(Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_WEB).'/api/soap/?wsdl');
  $sessionId = $proxy-&gt;login('API user','API Key');
  $tierPrices[] = array(
      'website'           =&gt; 'all',
      'customer_group_id' =&gt; 'all',
      'production_time    =&gt; $data[2],
      'qty'               =&gt; $data[3],
      'price'             =&gt; $data[4]
  );
   try {
          $proxy-&gt;call($sessionId, 'product_tier_price.update', array($sku, $tierPrices));
      } catch (Exception $e) {
          $e-&gt;getMessage() . "\n";
  }
  </code></pre>
  
  <p>I will get an error says "invalid tier price".</p>
  
  <p>Any idea why does it happen? or is there other ways to add tier prices?</p>
  
  <p>Thank you.</p>