Need ideas - detecting a "closed loop" on tilemap

// GetCheckTiles() returns a ScriptObject of class CHECKTILES.  This is a 6x6 array similar
      // to the SHAPE class, but it will define for any given shape: which tiles are adjacent to
      // a block in that shape?  Those are the tiles we need to run a CastleCheck() on.
      %checktiles = new ScriptObject() { class = "CHECKTILES"; }
      %checktiles = GetCheckTiles($GAME::CurrentShape);  ***SYNTAX ERROR HERE***
...
function GetCheckTiles(%shape)
{
   // create a checktiles object and initialize it with zeros
   %checktiles = new ScriptObject() { class = "CHECKTILES"; }
   for (%x=0;%x<6;%x++)
      for (%y=0;%y<6;%y++)
         %checktiles.check[%x,%y] = 0
   
   // examine the shape and set checktiles accordingly
   for (%x=1;%x<5;%x++)
      for (%y=1;%y<5;%y++)
         if (%shape.block[%x-1,%y-1] == 1)
         {
            // if this tile in the shape is a block, set every adjacent tile in the
            // checktiles to 1, except for other blocks.
            %checktiles.check[%x-1,%y] = 1 - %shape.block[%x-2,%y-1];
            %checktiles.check[%x-1,%y+1] = 1 - %shape.block[%x-2,%y];
            %checktiles.check[%x,%y+1] = 1 - %shape.block[%x-1,%y];
            %checktiles.check[%x+1,%y+1] = 1 - %shape.block[%x,%y];
            %checktiles.check[%x+1,%y] = 1 - %shape.block[%x,%y-1];
            %checktiles.check[%x+1,%y-1] = 1 - %shape.block[%x,%y-2];
            %checktiles.check[%x,%y-1] = 1 - %shape.block[%x-1,%y-2];
            %checktiles.check[%x-1,%y-1] = 1 - %shape.block[%x-2,%y-2];
         }
   return %checktiles;
}

%checktiles = new ScriptObject() { class = "CHECKTILES"; };