Android Material Design工具栏未在activity_main.xml中正确显示

Question

这是我的activity_main.xml

<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity">

<android.support.v7.widget.Toolbar
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/tb_main"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:minHeight="?attr/actionBarSize"
    android:background="?attr/colorPrimary"
    app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
</RelativeLayout>

这是我的styles.xml

<!-- Base application theme. -->
<style name="Theme.MyTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>

这是MainActivity.java

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;

public class MainActivity extends ActionBarActivity {
    private static String TAG = "LOG";
    private Toolbar mToolbar;
    private Toolbar mToolbarBottom;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mToolbar = (Toolbar) findViewById(R.id.tb_main);
    mToolbar.setTitle("Main Activity");
    mToolbar.setSubtitle("just a Subtitle");
    mToolbar.setLogo(R.drawable.ic_media_play);
    setSupportActionBar(mToolbar);
}

过去2天我一直试图解决这个问题。浅色工具栏未在屏幕上正确显示。 Android编程新手。任何建议都会有很大的帮助。