title: Report Builder shows only one row
body: <p>I created a report with multiple DataSets. The first dataset contains adresses and the second contains contact data like phone and email.
  So it is possible that a adress contains multiple contact items. But there is always only one contact item.
  I've created a Matrix where the Adressdata is in it. In this matrix is another matrix, which should list all contact items. 
  In both tables is a VaNr which is the Id for the adress. </p>
  
  <p>EDIT:
  I try to explain more details:
  I have the the table Adress which looks like this
  <a href="https://i.stack.imgur.com/btlYr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/btlYr.png" alt="enter image description here"></a></p>
  
  <p>As you can see there are some easy adress-data and the VaNr.
  John doe can have multiple contact data:</p>
  
  <p><a href="https://i.stack.imgur.com/WiJvu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WiJvu.png" alt="enter image description here"></a></p>
  
  <p>So in my report it should list john doe with three contacts. 
  I grouped my adress list with the VaNr. 
  <a href="https://i.stack.imgur.com/JTXrv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JTXrv.png" alt="enter image description here"></a></p>
  
  <p>The contact list for my adress is grouped to the VaNr:
  <a href="https://i.stack.imgur.com/MGbJb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MGbJb.png" alt="enter image description here"></a></p>
  
  <p>But this is the result I get:
  <a href="https://i.stack.imgur.com/2v8Y3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2v8Y3.png" alt="enter image description here"></a></p>
  
  <p>It only show one contact, but it should have three. There are three Contacts for John doe (with the same VaNr).</p>