Why am I not able to change the background color of my bottom navigation bar in Flutter?

I want to change the background color of my bottom navigation bar to black but yet it’s remaining white. What could be causing the issue?

Screenshot of the bottom navigation bar

Bottom navigation bar code.

bottomNavigationBar: BottomNavigationBar(
    onTap: _onItemTapped,
    type: BottomNavigationBarType.shifting,
    iconSize: 30,

    unselectedItemColor: Colors.black,
    selectedIconTheme: const IconThemeData(color: Colors.black, size: 30),
    selectedItemColor: Colors.black,
    selectedLabelStyle: const TextStyle(fontWeight: FontWeight.bold),
    backgroundColor: Colors.white,

    items: const <BottomNavigationBarItem>[
      BottomNavigationBarItem(
        icon: Icon(Icons.home),
        label: 'Home',
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.door_back_door),
        label: 'Rooms',
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.search),
        label: 'Search',
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.map),
        label: 'Maps',
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.person),
        label: 'Profile',
      ),
    ],
    currentIndex: _selectedIndex,
  ),

I’ve been trying to figure this part out and I can’t seem to see the reason of the issue. I’d appreciate any help if possible! 🙂