RelativeLayout trong Android

Các sư huynh cho em hỏi chút.
Vấn đề đặt ra là: Em muốn sử dụng RelativeLayout để thiết kế màn hình login theo kiểu
-ImageView
-EditText: Username
-EditText: Password
-LinearLayout: Button Login và Register

Code của em:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    tools:context="pomodoro.android7.ducthangwru.testpomodoro.activities.LoginActivity">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:scaleType="fitCenter"
        android:layout_marginBottom="16dp"/>

    <android.support.design.widget.TextInputLayout
        android:id="@id/et_username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@id/et_password">
        <EditText
            android:id="@+id/et_username"
            android:hint="@string/username"
            android:inputType="text"
            android:imeOptions="actionNext"
            android:maxLines="1"
            android:textSize="16sp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </android.support.design.widget.TextInputLayout>

    <android.support.design.widget.TextInputLayout
        android:id="@id/et_password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true">
        <EditText
            android:id="@+id/et_password"
            android:inputType="textPassword"
            android:imeOptions="actionDone"
            android:hint="@string/password"
            android:textSize="16sp"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </android.support.design.widget.TextInputLayout>

    <LinearLayout
        android:layout_gravity="center_horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/et_password">
        <Button
            android:id="@+id/bt_register"
            android:textColor="@color/colorAccent"
            android:background="#00000000"
            android:textAllCaps="false"
            android:layout_marginTop="@dimen/button_margin_top"
            android:layout_marginBottom="@dimen/button_margin_bottom"
            android:text="@string/register"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="@dimen/button_height" />
        <Button
            android:id="@+id/bt_login"
            android:background="@drawable/shape_button"
            android:textColor="#FFFFFF"
            android:textAllCaps="false"
            android:text="@string/login"
            android:layout_marginTop="@dimen/button_margin_top"
            android:layout_marginBottom="@dimen/button_margin_bottom"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="@dimen/button_height" />
    </LinearLayout>
</RelativeLayout>

Lỗi của em:

C:UsersDUC THANGAndroidStudioProjectsTestPomodoroappsrcmain
eslayoutactivity_login.xml
Error:(18, 21) No resource found that matches the given name (at 'id' with value '@id/et_username').
Error:(21, 31) No resource found that matches the given name (at 'layout_above' with value '@id/et_password').
C:UsersDUC THANGAndroidStudioProjectsTestPomodoroappuildintermediates
esmergeddebuglayoutactivity_login.xml
Error:(34, 21) No resource found that matches the given name (at 'id' with value '@id/et_password').
Error:(18, 21) No resource found that matches the given name (at 'id' with value '@id/et_username').
Error:(21, 31) No resource found that matches the given name (at 'layout_above' with value '@id/et_password').
Error:(34, 21) No resource found that matches the given name (at 'id' with value '@id/et_password').

Mong được các sư huynh giải đáp. Có gì không phải xin được lượng thứ.
Cảm ơn các sư huynh rất nhiều ạ!