onTap doesn't work in a widget I created outside of the main file in flutter

Question

I have three files: a widget.dart file where I create the widget that I named WalletItemMenu, another data_generator.dart file where I create a list of widgets that I have created and finally my main file main.dart where i use the list of WalletItemMenu created in data_generator.dart in a GridView.
widget.dart

InkWell WalletItemMenu(String titre,String img,MaterialColor? couleur){
  return InkWell(
    child: Container(
      child: Card(
        color: couleur,
        child: InkWell(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            crossAxisAlignment: CrossAxisAlignment.center,
            children: [
              Image.asset(img,height: 80),
              SizedBox(height: 10),
              Text(titre)
            ],
          ),
          onTap: (){print("ok");},
        ),
      ),
    ),
    onTap: (){print("ok");},
  );
}

In data_generator.dart I create a list of widgets WalletItemMenu
data_generator.dart

List<Widget> listeWalletItems(){
  List<Widget> list = [];
  var el1 = WalletItemMenu("Achat des unités",Ozangue_porte_monaie,Colors.yellow);
  list.add(el1);
  var el2 = WalletItemMenu("Transfert de crédit",Ozangue_porte_monaie,Colors.yellow);
  list.add(el2);
  var el3 = WalletItemMenu("Achat article",Ozangue_porte_monaie,Colors.yellow);
  list.add(el3);
  var el4 = WalletItemMenu("Echange d'argent",Ozangue_porte_monaie,Colors.yellow);
  list.add(el4);
  return list;
}

In the main file I try to create a GridView Containing the list of WalletItemMenu that I created beforehand in data_generator.dart.
main.dart

class MenuPorteMonaiePage extends StatefulWidget{

  @override
  _MenuPorteMonaiePageState createState() => _MenuPorteMonaiePageState();
}

class _MenuPorteMonaiePageState extends State<MenuPorteMonaiePage>{

  List<Widget> menus = [];

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    menus = listeWalletItems();
  }

  @override
  Widget build(BuildContext context){
    return Scaffold(
      backgroundColor: Colors.white,
      body: SingleChildScrollView(
              child: Container(
                height: 500,
                child: GridView.builder(
                  itemCount: menus.length,
                  gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                      crossAxisCount: 2,
                  ),
                  itemBuilder: (BuildContext context,int index){
                    return menus[index];
                  },
                ),
              ),
            )
    );
  }

The problem is that onTap does not work. How can I solve the problem? Thanks in advance.