{!! Form::text('agentName',null,['class'=>'form-control']) !!}

Shouldn't agent_name should be agentName?

Yes its correct but now my route is gone wrong when update it always gone 404. here is my route

###route

Route::controllers([
    'home' => 'HomeController',
    'validated/agent'=>'AgentController',
    '/' => 'WelcomeController',
]);

###contraoller

public function postEditAgent($id, EditAgentRequest $request)
    {
       $agent = Agents::findOrFail($id);
       $agent->agentName = $request->get('agentName');

       $agent->save();
       return redirect('validated/agent/')->with(['edited' => 'The agent was updated.']);
    }