Not able to call onLogin javascript function on heroku app

Hi All,

I am not able to call onLogin javascript function when I click on Login button.  <meta name="salesforce-login-handler" content="onLogin">

The user is able to login successfully but above meta tag is not calling the onLogin javascript function. The login button is just getting greyed out and I am not able to do anything after successful login.    

Please suggest any possible cause for that.  @David Brossard