title: Element was null when I user page object pattern
body: <p>I'm new to mobile automation, and I'm facing a problem with page object pattern. When I try to find element with FindElementById everything works, here is my class with pop:</p>
  <pre><code>public class SamplePage
      {
          private AndroidDriver&lt;AndroidElement&gt; _driver;
  
          [FindsByAndroidUIAutomator(ID = &quot;com.miui.calculator:id/btn_1_s&quot;)]
          private readonly AndroidElement _buttonOne;
  
          [FindsByAndroidUIAutomator(ID = &quot;android:id/button1&quot;)]
          private readonly AndroidElement _confirmButton;
  
          public SamplePage(AndroidDriver&lt;AndroidElement&gt; driver)
          {
              _driver = driver;
              PageFactory.InitElements(_driver, this);
          }
  
          public void ClickOnConfirmButton()
          {
              //AndroidElement _confirmButton = _driver.FindElementById(&quot;android:id/button1&quot;);
              _confirmButton.Click();
          }
  
          public void ClickOnButtonOne()
          {
              //AndroidElement _buttonOne = _driver.FindElementById(&quot;com.miui.calculator:id/btn_1_s&quot;);
              _buttonOne.Click();
             
          }
  
      }
  </code></pre>
  <p>And here is main class</p>
  <pre><code>using NUnit.Framework;
  using OpenQA.Selenium;
  using OpenQA.Selenium.Appium;
  using OpenQA.Selenium.Appium.Enums;
  using OpenQA.Selenium.Appium.Android;
  using OpenQA.Selenium.Remote;
  using System;
  using AppiumDotNetSamples.Helper;
  
  namespace AppiumDotNetSamples
  {
      [TestFixture()]
      public class AndroidBasicInteractionsTest
      {
          private AndroidDriver&lt;AndroidElement&gt; driver;
          private SamplePage _samplePage;
  
          [SetUp()]
          public void BeforeAll()
          {
              DesiredCapabilities capabilities = new DesiredCapabilities();
              capabilities.SetCapability(MobileCapabilityType.PlatformName, &quot;Android&quot;);
              capabilities.SetCapability(MobileCapabilityType.PlatformVersion, &quot;7.1.2&quot;);
              capabilities.SetCapability(MobileCapabilityType.AutomationName, &quot;UIAutomator2&quot;);
              capabilities.SetCapability(MobileCapabilityType.DeviceName, &quot;3e52f2ee7d34&quot;);
              capabilities.SetCapability(&quot;appPackage&quot;, &quot;com.miui.calculator&quot;);
              capabilities.SetCapability(&quot;appActivity&quot;, &quot;com.miui.calculator.cal.CalculatorActivity&quot;);
             
              driver = new AndroidDriver&lt;AndroidElement&gt;(new Uri(&quot;http://localhost:4723/wd/hub&quot;), capabilities, TimeSpan.FromSeconds(180));
              driver.Manage().Timeouts().ImplicitWait = TimeSpan.FromSeconds(10);
  
              _samplePage = new SamplePage(driver);
          }
  
          [Test()]
          public void Click()
          {
              _samplePage.ClickOnConfirmButton();
              _samplePage.ClickOnButtonOne();
          }
  
          [TearDown()]
          public void AfterAll()
          {
              driver.Quit();
          }
          
      }
  }
  </code></pre>
  <p>What am I doing wrong? I test on on Xiaomi Calculator app, but earlier I got the same issues on any other app like Google Calculator.</p>