We recently had to patch the SQL Servers for SharePoint to allow Power View to use cubes (CU #4).

After a few minutes of worrying, because the patching didn’t seem to work. We realized that we hadn’t put the SQL Server CU on the SharePoint server (any server you installed the Reporting Services Add-in on). When you install the patch it doesn’t show the Reporting Service in the options to install. But when it finishes installing the Completed tab shows the below and problem solved!