Gridview.count Flutter not working and showing yellow and black stripes - flutter

Question

I did a Gridview.count for rendering 6 buttons in 2 columns and 3 rows, it's not rendering and instead of the components, it shows yellow and black stripes. I already set the height and the width, all wrapped in a container.
return Scaffold(
body: Container(
height: 450.0,
width: double.infinity,
child: GridView.count(
shrinkWrap: true,
primary: true,
crossAxisCount: 2,
children: <Widget>[
Center(
child: FlatButton(
onPressed: () => {},
padding: EdgeInsets.all(10.0),
child: Column(children: <Widget>[
Image.asset(
'assets/img/wifi.png',
height: 50.0,
width: 50.0,
),
Text('Wifi')
]),
),
),
Center(
child: FlatButton(
onPressed: () => {},
padding: EdgeInsets.all(10.0),
child: Column(children: <Widget>[
Image.asset(
'assets/img/wifi.png',
height: 50.0,
width: 50.0,
),
Text('Key/Access')
]),
),
),
Center(
child: FlatButton(
onPressed: () => {},
padding: EdgeInsets.all(10.0),
child: Column(children: <Widget>[
Image.asset(
'assets/img/wifi.png',
height: 50.0,
width: 50.0,
),
Text('Key/Access')
]),
),
),
Center(
child: FlatButton(
onPressed: () => {},
padding: EdgeInsets.all(10.0),
child: Column(children: <Widget>[
Image.asset(
'assets/img/wifi.png',
height: 50.0,
width: 50.0,
),
Text('Key/Access')
]),
),
),
],
)));
}
}
Please, someone knows why it's not rendering properly? or have an alternative widget that might work better? Thanks.
This widget is imported in this one:
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Color(0xFF88B4E0),
appBar: AppBar(
leading: IconButton(
onPressed: () {
Navigator.of(context).pop();
},
icon: Icon(Icons.arrow_back_ios),
color: Colors.white,
),
backgroundColor: Colors.transparent,
elevation: 0.0,
title: Text('Help and FAQ',
style: TextStyle(fontSize: 18.0, color: Colors.white)),
centerTitle: true,
actions: <Widget>[
SearchButton(),
],
),
body: ListView(children: [
Stack(children: [
Container(
height: MediaQuery.of(context).size.height - 82.0,
width: MediaQuery.of(context).size.width,
color: Colors.transparent),
Positioned(
top: 75.0,
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.only(
topLeft: Radius.circular(45.0),
topRight: Radius.circular(45.0),
),
color: Colors.white),
height: MediaQuery.of(context).size.height - 100.0,
width: MediaQuery.of(context).size.width,
child: Column(
children: [
SizedBox(height: 20.0),
Testing(),
],
),
)),
]),
]),
);
}
void moveBack() {
Navigator.pop(context);
}
}