Hi Juneed,
So you are saying that you are not able to preview the dashboard in the designer? Just to confirm, you are able to get pass the logon screen that you screenshot?
If the dashboard doesn't load in the designer then there is an issue with the data connection or the data source query. Are you using BICS to connect to BW? If you are, are you able to edit the data sources and preview the data in the connection editor?
If that doesn't work either, open Web Intelligence and connect to the same data source and recreate the query and see if it works in Webi.
Regards,
Josh