Android MapView not loading tiles on devices

I am writing an Android application that uses Google Maps MapView to display maps. The application works fine in the emulator, but when I try to run it on an actual device it will not load any map tiles.

I have already done the following:

• Checked that Eclipse ADT is configured with the default debug keystore
• I have regenerated the Google Maps API key against the debug keystore
• Checked that the application has access to the internet for the application also connects to a different server and that works ok.
• I have checked and re-checked all the tips that are found in other similar question, but in case I have missed anything I have attached the res/layout file and the android manifest file.

Layout file

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/mainlayout"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <com.google.android.maps.MapView
        android:id="@+id/mapview"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:clickable="true"
        android:apiKey="0AVJ6OY3X1uWHCbkTOJx7ajC-TWI44phQofTSlg"
    />                  
</RelativeLayout>

Android Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.example.android"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-sdk android:minSdkVersion="7" />

    <application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="true">
        <uses-library android:name="com.google.android.maps" android:required=开发者_运维技巧"true"/>
        <activity android:name="DummyMap"
                  android:label="@string/app_name">
        </activity>        
        <activity android:name="Dummy" android:label="@string/app_name" android:theme="@android:style/Theme.Light">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>        
        </activity>
        <activity android:name="ContactActivity" android:theme="@android:style/Theme.Light"></activity>
        <activity android:name="DummyPreferences"></activity>
    </application>
</manifest>

Any tips are welcome as I am now at the point where I have to randomly try to make changes to these file to see if anything works.

I see in Android reference document (http://developer.android.com/reference/android/Manifest.permission.html#ACCESS_COARSE_LOCATION):

ACCESS_COARSE_LOCATION Allows an application to access coarse (e.g., Cell-ID, WiFi) location

But because you're running app on device, so you should add additional permission: ACCESS_FINE_LOCATION because with this permission, your device can get location by GPS

ACCESS_FINE_LOCATION Allows an application to access fine (e.g., GPS) location

I found the cause of the problem at last.

In my subclass of MapActivity I had a onResume() method that called super.onStop()! Changing that to super.onResume() fixed the problem.