title: Matlab Simulink Error with get_param
body: <p>I dont understand this error : even it is the S-function , why it works at first with " sous_systems{i_sous_system} " but when I put the path directly not ?</p>
  
  <p>K>> sous_systems{i_sous_system}</p>
  
  <p>ans =</p>
  
  <p>F0_Model/F10_01_NOK</p>
  
  <p>K>> lines = get_param(sous_systems{i_sous_system}, 'Lines')</p>
  
  <p>lines = </p>
  
  <p>2x1 struct array with fields:</p>
  
  <pre><code>Handle
  Name
  Parent
  SrcBlock
  SrcPort
  DstBlock
  DstPort
  Points
  Branch
  </code></pre>
  
  <p>K>> lines = get_param(F0_Model/F10_01_NOK , 'Lines')
  Error in S-function 'F0_Model/F10_01_NOK /S-Function': S-Function
  'system' does not exist</p>