The way is to first go to the data manage and go to the connection in dashboard.There we see the wsdl url and the web service url.Do not touch the wsdl url.Only we need to remove http://server port from the web service url.
So the web service url will look like /dswsbobje/queryasservice....... like this.
Now sabe the dashboard to platform.
It should work in the BI Launchpad.
It will not work when its previewed in designer as web service path is relative