diff --git a/grid/albertagrid/albertagrid.cc b/grid/albertagrid/albertagrid.cc
index 90bb3305e4f48f4918664c8b6ff8b74a280cfd1e..6b970895a843269151339f4b05316ce911410e09 100644
--- a/grid/albertagrid/albertagrid.cc
+++ b/grid/albertagrid/albertagrid.cc
@@ -2163,7 +2163,6 @@ namespace Dune
       manageStack_.makeItNew(true);
 
       virtualEntity_.setTraverseStack(manageStack_.getStack());
-      std::cout << manageStack_.getStack() << " TStack is \n";
 
       // diese Methode muss neu geschrieben werden, da man
       // die ParentElement explizit speichern moechte.
@@ -2848,7 +2847,6 @@ namespace Dune
     // sich deshalb die Werte anedern koennen, der elinfo_stack bleibt jedoch
     // der gleiche, deshalb kann man auch nur nach unten, d.h. zu den Kindern
     // laufen
-    std::cout << travStack_ << "Traverse Stack \n";
     return AlbertaGridHierarchicIterator<GridImp> (grid_,travStack_,level(),maxlevel);
   }
 
@@ -3509,7 +3507,7 @@ namespace Dune
 
   template<int dim, int dimworld>
   inline bool AlbertaGrid < dim, dimworld >::
-  mark( int refCount , typename Traits::template codim<0>::EntityPointer & ep )
+  mark( int refCount , typename Traits::template codim<0>::EntityPointer & ep ) const
   {
     return this->mark(refCount,*ep);
   }
@@ -3524,9 +3522,11 @@ namespace Dune
 
   template<int dim, int dimworld>
   inline bool AlbertaGrid < dim, dimworld >::
-  mark( int refCount , typename Traits::template codim<0>::Entity & ep )
+  mark( int refCount , const typename Traits::template codim<0>::Entity & ep ) const
   {
     ALBERTA EL_INFO * elInfo = (this->template getRealEntity<0>(ep)).getElInfo();
+    if(!elInfo) return false;
+    //std::cout << elInfo << "\n";
     assert(elInfo);
     if( ep.isLeaf() )
     {
@@ -3549,12 +3549,15 @@ namespace Dune
         return true;
       }
     }
-    // only for debugging
-    else
-    {
-      fprintf(stderr,"ERROR in AlbertaGridEntity<0,%d,%d>::mark(%d) : called on non LeafEntity! in: %s line: %d \n",dim,dimworld,refCount,__FILE__,__LINE__);
-      abort();
-    }
+    /*
+       // only for debugging
+       else
+       {
+       derr << "ERROR in AlbertaGridEntity<0,"<<dim<<","<<dimworld<<">::mark("<<refCount<<") : called on non LeafEntity! in: " << __FILE__ << " line: "<< __LINE__ << "\n";
+       assert(false);
+       abort();
+       }
+     */
     elInfo->el->mark = 0;
     return false;
   }