error shows up after removing child

this is the code that changes the depth of char.  I move the tree depth front and back depending on charShadow.y

after the evil death thing, charShadow doesn't change but char depth jumps to the top

for(var treeNum:int = treeshadows.length-1;treeNum>=0;treeNum--)

    {

     for(var someTrees:int = trees.length-1;someTrees>=0;someTrees--)

     {

      if(char.hitTestObject(trees[someTrees]))

      {

      if(charShadow.y < treeshadows[treeNum].y)

      {

       this.setChildIndex(trees[someTrees], this.numChildren-1);

      }

      if(charShadow.y > treeshadows[treeNum].y)

      {

       this.setChildIndex(trees[someTrees], this.numChildren-4);

      }

      }

      else

      {

      }

     }