Custom field fetch in items fails

Custom field fetch in items fails

Hey Zoho Community, 

I've created a custom module in Zoho books which is called "Storage Bins".  I'm looking up this custom module in ITEMS under the label "Bin Number" 


In a custom function I want to fetch the value (Which I assume is the ID of the object in the custom module). For some reason I'm receiving null only. I either have a code issue or somethings wrong - maybe because it's still on beta? 

Here's my code: 
  2. //Standard fields fetch
  3. itemName = item.get("name");
  4. itemID = item.get("item_id");
  5. orgID = organization.get("organization_id");


  8. //Fetch custom fields
  9. item_custom_fields_initial = item.get("custom_fields").toList();
  10. for each  item_custom_field_initial in item_custom_fields_initial
  11. {
  12. if(item_custom_field_initial.toMap().get("label") == "Bin Number")
  13. {
  14. bin_id = item_custom_field_initial.get("value");
  15. }
  16. break;
  17. }

  19. resultMap = Map();
  20. resultMap.put("message","Item Name : " + itemName + " ID " + itemID + " Bin ID " + bin_id);
  21. resultMap.put("code",0);

  23. return resultMap;

I tried using the API name which didn't work either.

Thanks heaps for your reply. 
Ben