There are several UI gotchas related to building PowerView visualizations that I wanted to address with this post. First, PowerView is not available in the Ribbon out of the box, in order to enable it, one needs to go to File->Options->Add-ins. Then find Manage Add-Ins drop down box, select “COM Ad-ins” and click Go. That brings a window up that allows us to check PowerView box to enable it.
Once enabled, the PowerView button is now available
Now that PowerView is enabled, what can we do with it? Well, if the workbook happens to have a PowerPivot model in it, clicking the PowerView icon will create a new worksheet with the PowerView experience in it against that PowerPivot model. If the workbook does not have a PowerPivot model in it, you will be staring at a blank PowerView worksheet with no data to explore. This is where things get confusing, since there is no way to specify connection to an existing Analysis Services cube from here.
In order to connect to the Analysis Services model (I still call them cube even in Tabular mode), one should click on Data->Existing connections. That brings up a list of existing connections, (click on Data->From Other Sources->From Analysis Services to create one), pick a connection to your tabular model and click Open. That will bring up a screen that will look like this:
Now you can select Power View report and off you go!
business intelligist 
Good one.. thanks.. i spend couple of days to know this…useful
For someone working in BI you shouldknow your terminology.
SSAS Tabular & Multidemsional models are 2 completely seperate things. Only multidemsional models are refered to as “cubes”.
Power View in a stand alone install of on-premise Excel (wqhbased on your screen shots is what you are refering to) can *only* connect to a SSAS Tabular model therefore Pwer View in Excel cannot connect to “cubes”.
pourquoi dans Excel Power View ne se connecte pas à des cubes?
aidez-moi s’il vous plait