title: Infopath: Rules with Multiple Selection List Box do not trigger
body: <p>Im trying to implement several rules for a form, based on a selection of some multiple selection list boxes. Im customizing a form for a existing SharePoint list by clicking on "Customize Form" in SharePoint. First of all, the choice fields on the list (multiple selection) are oddly binded in InfoPath:</p>
  
  <p><a href="https://i.stack.imgur.com/qW1eh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qW1eh.png" alt=""></a></p>
  
  <p>I cant change the variable's name "Value" and Real Estate Categories should not be a required field. (*) </p>
  
  <p>On one view I have a "Business Unit Purchase" box that is a multiple selection box (choice) and there is a next button. The next button should only be availiable when a selection is made.</p>
  
  <p>So I tried to the following rules for the Next Button:</p>
  
  <pre><code>Rule Type Action:
  
  IF Value (of Business Unit Pruchase) is not blank -&gt; Switch to next view
  </code></pre>
  
  <p>This works properly, but now i wanted to disable the next button when nothing is the text box was selected, because it makes it more clear to have a selection beofre ist possible to go on. So I tried this:</p>
  
  <pre><code>Rule Type Formatting:
  
  IF Value is blank -&gt; disable this control
  </code></pre>
  
  <p>This disables the button as wanted when the multiple text box has not any items selected, but after selecting one or more, nothing happens. Is there any reason why this does not work?</p>
  
  <p>Normally when a selection is made, the field "value" of "Business Unit Purchase" should contain one or more strings and therefor should not be blank anymore.</p>