E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: mx.iteso.erickgarcia.practica8, PID: 10495
                  java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
                      at mx.iteso.erickgarcia.practica8.FragmentAddUser.onCreateView(FragmentAddUser.java:30)
                      at android.app.Fragment.performCreateView(Fragment.java:2353)
                      at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:995)
                      at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1171)
                      at android.app.BackStackRecord.run(BackStackRecord.java:815)
                      at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1578)
                      at android.app.FragmentManagerImpl$1.run(FragmentManager.java:483)
                      at android.os.Handler.handleCallback(Handler.java:751)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:154)
                      at android.app.ActivityThread.main(ActivityThread.java:6077)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)