public function main($id)
 {
     if (is_null(Agent::find($id))) {
         return Redirect::to('admin');
     }
     $commissions = Commission::where('agent_id', $id)->orderBy('created_at', 'desc')->get();
     $agent = Agent::find($id);
     View::make('admin.commission.list', compact('commissions', 'agent'));
 }