diff --git a/Modules/IGT/IO/mitkNavigationDataPlayerBase.cpp b/Modules/IGT/IO/mitkNavigationDataPlayerBase.cpp
index 8a364da16e..3452bc0ce5 100644
--- a/Modules/IGT/IO/mitkNavigationDataPlayerBase.cpp
+++ b/Modules/IGT/IO/mitkNavigationDataPlayerBase.cpp
@@ -1,115 +1,109 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #include "mitkNavigationDataPlayerBase.h"
 
 // include for exceptions
 #include "mitkIGTException.h"
 
 mitk::NavigationDataPlayerBase::NavigationDataPlayerBase()
   : m_NumberOfOutputs(0)
 {
   m_Name ="Navigation Data Player Source";
 }
 
 mitk::NavigationDataPlayerBase::~NavigationDataPlayerBase()
 {
 }
 
 void mitk::NavigationDataPlayerBase::UpdateOutputInformation()
 {
   this->Modified();  // make sure that we need to be updated
   Superclass::UpdateOutputInformation();
 }
 
-
 bool mitk::NavigationDataPlayerBase::IsAtEnd()
 {
   return m_NavigationDataSetIterator == m_NavigationDataSet->End();
 }
 
 void mitk::NavigationDataPlayerBase::SetNavigationDataSet(NavigationDataSet::Pointer navigationDataSet)
 {
   m_NavigationDataSet = navigationDataSet;
   m_NavigationDataSetIterator = navigationDataSet->Begin();
 
   this->InitPlayer();
 }
 
 unsigned int mitk::NavigationDataPlayerBase::GetNumberOfSnapshots()
 {
   return m_NavigationDataSet.IsNull() ? 0 : m_NavigationDataSet->Size();
 }
 
 unsigned int mitk::NavigationDataPlayerBase::GetCurrentSnapshotNumber()
 {
   return m_NavigationDataSet.IsNull() ? 0 : m_NavigationDataSetIterator - m_NavigationDataSet->Begin();
 }
 
 void mitk::NavigationDataPlayerBase::InitPlayer()
 {
   if ( m_NavigationDataSet.IsNull() )
   {
     mitkThrowException(mitk::IGTException)
-        << "NavigationDataSet has to be set before initializing player.";
+      << "NavigationDataSet has to be set before initializing player.";
   }
 
-
   if (m_NumberOfOutputs == 0)
   {
-    m_NumberOfOutputs = m_NavigationDataSet->GetNumberOfTools();
-    this->SetNumberOfRequiredOutputs(m_NumberOfOutputs);
+    int requiredOutputs = m_NavigationDataSet->GetNumberOfTools();
+    this->SetNumberOfRequiredOutputs(requiredOutputs);
 
-    for (unsigned int n = 0; n < m_NumberOfOutputs; ++n)
+    for (unsigned int n = this->GetNumberOfOutputs(); n < requiredOutputs; ++n)
     {
-      mitk::NavigationData* output = this->GetOutput(n);
-      if (!output)
-      {
-        DataObjectPointer newOutput = this->MakeOutput(n);
-        this->SetNthOutput(n, newOutput);
-        this->Modified();
-      }
+      DataObjectPointer newOutput = this->MakeOutput(n);
+      this->SetNthOutput(n, newOutput);
+      this->Modified();
     }
   }
   else if (m_NumberOfOutputs != m_NavigationDataSet->GetNumberOfTools())
   {
     mitkThrowException(mitk::IGTException)
-        << "Number of tools cannot be changed in existing player. Please create "
-        << "a new player, if the NavigationDataSet has another number of tools now.";
+      << "Number of tools cannot be changed in existing player. Please create "
+      << "a new player, if the NavigationDataSet has another number of tools now.";
   }
 
   this->Modified();
 }
 
 void mitk::NavigationDataPlayerBase::GraftEmptyOutput()
 {
   for (unsigned int index = 0; index < m_NavigationDataSet->GetNumberOfTools(); index++)
   {
     mitk::NavigationData* output = this->GetOutput(index);
     assert(output);
 
     mitk::NavigationData::Pointer nd = mitk::NavigationData::New();
     mitk::NavigationData::PositionType position;
     mitk::NavigationData::OrientationType orientation(0.0,0.0,0.0,0.0);
     position.Fill(0.0);
 
     nd->SetPosition(position);
     nd->SetOrientation(orientation);
     nd->SetDataValid(false);
 
     output->Graft(nd);
   }
-}
+}
\ No newline at end of file