Xrm.Page.getControl("fieldname").clearNotification() is not working in Dynamics 365?

Hi All,

I am using    Xrm.Page.getControl("fieldname").setNotification("Invalid");  for show the error notification on field in JavaScript. It is working fine.

But Xrm.Page.getControl("cyno_startdate").clearNotification() is not working for clear notification in Dynamics 365. 

If, I am using this alert(Xrm.Page.getControl("cyno_startdate").setNotification("Invalid Start Date")). Its return false.

Please suggest any solution ASAP.

Thanks!