how to access to mxml component through another mxml

Question

Hi all I have an mxml canvas component with grid and I have in the mx:Script tag a public function that add a GridItem child into the grid. When I call this public function thorugh my main application and run the project, it stuck. so how can I do this? how to change my grid in the canvas through my main application and why my code doesn't work. Thank you guys. Regrads. elad.

my code:

the grid in the canvas:

mx:Grid left="10" right="10" top="92" bottom="26" id="grid" borderStyle="solid" borderColor="#545454" 

/mx:Grid

the public function in the same mxml:

     public function SetGrid(rows:int, columns:int):void
   {
    for (var i:int=0;i>rows;i++)
    {
     var newGridRow:GridRow = new GridRow();
     for (var j:int=0;j&gtcolumns;j++)
     {
      var newGridItem:GridItem = new GridItem();
      newGridItem.id = "i-j";
      newGridRow.addChild(newGridItem);
     }
     grid.addChild(newGridRow);
    }
   }