Flutter : onPressed for imagepicker function not working

I built an image picker after learning in a course. I am not getting any errors in the debug console or in the build. I am trying to click it but it is not working. I made another image picker in a similar manner in same app but that did not gave any error

My add image screen:

  bool uploading = false;
  double val = 0;
  CollectionReference? imgRef;
  firebase_storage.Reference? ref; 

  List<File> _image = []; 
  final picker = ImagePicker();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Add Image'),
        actions: [
          ElevatedButton(
            onPressed: () {
              setState(() {
                uploading = true;
              });
              
              uploadFile().whenComplete(() => Navigator.of(context).pop());
            },
            child: Text(
              'Upload',
              style: TextStyle(color: Colors.red),
            ),
          )
        ],
      ),
      body: Stack(children: [
        GridView.builder(
            itemCount: _image.length + 1,
            gridDelegate:
                SliverGridDelegateWithMaxCrossAxisExtent(maxCrossAxisExtent: 1),
            itemBuilder: (ctx, i) {
              return i == 0
                  ? Center(
                      child: IconButton(
                          onPressed: () {
                            !uploading ? chooseImage() : null;
                          },
                          icon: Icon(Icons.add)),
                    )
                  : Container(
                      margin: EdgeInsets.all(3),
                      decoration: BoxDecoration(
                          image:
                              DecorationImage(image: FileImage(_image[i - 1]))),
                    );
            }),
        uploading
            ? Center(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Container(
                        child: Text('uploading...',
                            style: TextStyle(fontSize: 20))),
                    CircularProgressIndicator.adaptive(
                      
                      value: val,
                      valueColor: AlwaysStoppedAnimation<Color>(Colors.green),
                    )
                  ],
                ),
              )
            : Container()
      ]),
    );
  } ```


Choose image function :
```chooseImage() async {
    
    final pickedFile = await picker.pickImage(source: ImageSource.gallery);
    setState(() {
      _image.add(File(pickedFile!.path));
    });
    if (pickedFile!.path == null) retrieveLostData();
  }```

I tried onPressed: chooseImage; but it still did not work