Odata & json - CRM upgrade to 2013 give warning

Hi,

I am upgrading CRM 2011 to CRM 2013 and changed old java scripts to Odata &  json but still giving warning when run custom code validation tool for CRM 2013.

Xrm.Page.getAttribute("new_department").setValue(retrieved.results[0].new_Department.Value);

I want to further upgrade from CRM 2013 to CRM 2015 then CRM 2016.  Will this make any issue.  Please provide the solution.