Hey, I created a custom view for a list item. at its own file the buttons work but when I use the view on my list view, it does not work. Can someone explain to me why it is not working?

import SwiftUI

struct itemBox: View {
    @ObservedObject var item = Item(itemName: "", itemCount: 0)

    var body: some View {

        VStack{
            Text("\(item.itemName ?? "Enter Name")")
                .padding([.top, .leading, .trailing])
               HStack {

                Button ( action:{
                    item.add()
                }, label: {
                    Image(systemName: "arrowtriangle.up.square.fill")
                        .frame(width: 19.0, height: 19.0)
                        .imageScale(.large)
                        .foregroundColor(.accentColor)
                })
                .padding([.leading, .bottom])

                   Text("\(item.itemCount)")

                Button ( action:{
                    item.sub()
                }, label: {
                    Image(systemName: "arrowtriangle.down.square.fill")
                        .frame(width: 19.0, height: 19.0)
                        .imageScale(.large)
                        .foregroundColor(.accentColor)
                        .background(item.itemCount == 0 ? Color.gray : Color.blue)
                }).padding([.bottom, .trailing]) .disabled(item.itemCount == 0)
            }

        }.frame(width: 100.0, height: 100.0)
            .border(/*@START_MENU_TOKEN@*/Color.yellow/*@END_MENU_TOKEN@*/, width: /*@START_MENU_TOKEN@*/6/*@END_MENU_TOKEN@*/)

    }
}

import SwiftUI

struct ContentView: View {

    @State private var showingPopup = false
    @ObservedObject var item = Item(itemName: "", itemCount: 0)

    var body: some View {
        NavigationStack{
            List(Item.sample) { item in
                itemBox(item: item)
            }            .toolbar {
                ToolbarItemGroup(placement: .navigationBarLeading) {
                    Button("Add new") {
                        self.showingPopup = true
                        print("dsds")
                    }.sheet(isPresented: $showingPopup, content: {
                        ListView()
                    })
                }

                ToolbarItemGroup(placement: .navigationBarTrailing) {
                    Button("Item List") {
                        self.showingPopup = true
                        print("dsds")
                    }.sheet(isPresented: $showingPopup, content: {
                        ListView()
                    })
                }
            }

            .navigationBarBackButtonHidden(true)
        }
    }

}

Thank you very much.