title: Why do PowerPivots with multiple sources not show the correct data unless something is added to the Values list?
body: <p>I have three tables: </p>
  
  <p>Person</p>
  
  <p><a href="https://i.stack.imgur.com/GLKmim.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GLKmim.png" alt="enter image description here"></a></p>
  
  <p>Event</p>
  
  <p><a href="https://i.stack.imgur.com/cHKTrm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cHKTrm.png" alt="enter image description here"></a></p>
  
  <p>PersonEvent</p>
  
  <p><a href="https://i.stack.imgur.com/fxyjfm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fxyjfm.png" alt="enter image description here"></a></p>
  
  <p>Persons attend Events. This many-to-many relationship is modeled by the junction table PersonEvent, which also records Hours Spent on the Event. I added each of these tables to the Data Model, which looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/00ZNdm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/00ZNdm.png" alt="enter image description here"></a></p>
  
  <p>I want to see which Persons attended which Events. The PowerPivot shows every Person as attending every Event, which is obviously wrong:</p>
  
  <p><a href="https://i.stack.imgur.com/jJkUVm.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jJkUVm.png" alt="enter image description here"></a></p>
  
  <p>Only when I add the Sum of Hours Spent to the PowerPivot does the correct information display:</p>
  
  <p><a href="https://i.stack.imgur.com/lqU35m.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lqU35m.png" alt="enter image description here"></a></p>
  
  <p>Why?</p>