Getting NullPointerException when tried to test two different pages

I am new to automation testing and I have been stuck on testing two different pages (HomePage and AboutPage) Here I have my code http://ift.tt/2u7gH0A Here is stacktrace

java.lang.NullPointerException
    at org.openqa.selenium.support.pagefactory.DefaultElementLocator.findElement(DefaultElementLocator.java:69)
    at org.openqa.selenium.support.pagefactory.internal.LocatingElementHandler.invoke(LocatingElementHandler.java:38)
    at com.sun.proxy.$Proxy11.click(Unknown Source)
    at pages.HomePage.verifyAboutPage(HomePage.java:37)
    at tests.AboutPageTest.aboutPage(AboutPageTest.java:27)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:80)
    at org.testng.internal.Invoker.invokeConfigurationMethod(Invoker.java:564)
    at org.testng.internal.Invoker.invokeConfigurations(Invoker.java:213)
    at org.testng.internal.Invoker.invokeMethod(Invoker.java:653)
    at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:901)
    at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1231)
    at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:127)
    at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:111)
    at org.testng.TestRunner.privateRun(TestRunner.java:767)
    at org.testng.TestRunner.run(TestRunner.java:617)
    at org.testng.SuiteRunner.runTest(SuiteRunner.java:334)
    at org.testng.SuiteRunner.access$000(SuiteRunner.java:37)
    at org.testng.SuiteRunner$SuiteWorker.run(SuiteRunner.java:368)
    at org.testng.internal.thread.ThreadUtil$2.call(ThreadUtil.java:64)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)




Test ignored.JavaScript error: resource://gre/components/nsUrlClassifierListManager.js, line 287: NS_ERROR_NOT_INITIALIZED: Component returned failure code: 0xc1f30001 (NS_ERROR_NOT_INITIALIZED) [nsIUrlClassifierDBService.getTables]
JavaScript error: resource://gre/components/nsUrlClassifierListManager.js, line 287: NS_ERROR_NOT_INITIALIZED: Component returned failure code: 0xc1f30001 (NS_ERROR_NOT_INITIALIZED) [nsIUrlClassifierDBService.getTables]
1498838795121   Marionette  INFO    Ceased listening

But if I change testng.xml to test one of my classes it's work just fine