Adding Column widget in ModalBottomSheet showing Transparent View- Flutter

I have to show ModalBottomSheet with this widget : showModalBottomSheet

For that I set all the required properties of ModalBottomSheet and as a builder part I am doing it as below :

builder: (_) {
      return Column(
        children: [
          Text("Sample "),
          ListView.builder(
              itemCount: 2,
              itemBuilder: (BuildContext context, int index) {
                return NagarTiming();
              }),
        ],
      );
    }

You can see that There is a Text widget inside Column widget which I have used there to consider it as a Title of my ModalBottomSheet.

But unfortunately, when I execute or call showModalBottomSheet method, Its showing me just transparent window or view.

Note that without Column widget and Text widget If I return only ListView as builder for ModalBottomSheet, Its working fine for me.

What might be the issue in showing Title (Text in Column widget) ?

It was the issue with the vertical size. ListView inside Column widget should have height concern. So used Flexible widget as below :

builder: (_) {
      return Column(
        children: [
          Text("Sample "),
          Flexible(
          child: ListView.builder(
              itemCount: 2,
              itemBuilder: (BuildContext context, int index) {
                return NagarTiming();
              }),
          ),
        ],
      );
    }