FindsBy from SeleniumExtras can't find IWebElement

Question

I've updated packages from my project on Mac and find out that PageObjects has been moved to SeleniumExtras. I struggle to use it but the error "System.NullReferenceException : Object reference not set to an instance of an object." is shown. Nevertheless, the same element can be found through FindElement. Currently, I run out of ideas and would appreciate the help. Thanks!

using Microsoft.VisualStudio.TestTools.UnitTesting;
using NUnit.Framework;
using NUnit.Compatibility;
using OpenQA.Selenium;
using OpenQA.Selenium.Chrome;
using SeleniumExtras.PageObjects;


namespace SomeTest
{
    [TestFixture]
    public class UnitTest1
    {
        [FindsBy(How = How.XPath, Using = "//*[@id='lst-ib']")]
        public IWebElement _searchField;

        public IWebDriver chrome;

        [SetUp]
        public void TestMethod1()
        {
            chrome = new ChromeDriver(@"/Volumes/Macintosh HD/QA/SomeTest/SomeTest/bin/Debug/netcoreapp2.1");
        }
        [Test]
        public void SomeTest()
        {
            chrome.Navigate().GoToUrl("https://www.google.com/");
            _searchField.SendKeys("Some Text");
        }
        [TearDown]
        public void CloseBrowser()
        {
            chrome.Close();
        }
    }
}

Answer 1

Got solution:

1. Add all DotNetSeleniumExtras through NuGet Packages: PageObjects and PageObjects.Core;
2. Add namespaces: using FindsByAttribute = SeleniumExtras.PageObjects.FindsByAttribute; using How = SeleniumExtras.PageObjects.How;