Power BI Embed report JavaScript

I am trying to use power bi Javascript SDK to embed my report(import report with dataset setup and refresh using on-premise gateway), for instance use https://microsoft.github.io/PowerBI-JavaScript/demo/v2-demo/index.html
I got all Embed Token, URL and Report Id, but when i run the script, i get OpenConnectionError.
i.e. 

> Loaded
> Json Object
{
"message": "Could not render a report visual titled Test",
"detailedMessage": "Can't display the visual.",
"errorCode": "OpenConnectionError",
"technicalDetails": {
"requestId": "7092a030-e0e3-8768-ef34-2646561b0763"
}
}

What could be probable reason and missings that i have done?
Thanks in advance.