What does “Failure [INSTALL_FAILED_OLDER_SDK]” mean in Android Studio?

I got this Froyo (2.2) device that I am using to make an app. When I try to run the app directly to the device it shows an error saying

pkg: /data/local/tmp/com.example.HelloWorldProject
Failure [INSTALL_FAILED_OLDER_SDK]

and in another window there’s an error saying

Unable to attach test reporter to test framework or test framework quit unexpectedly

What seem to make the said errors?

EDIT:

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.test.helloworld"
          android:versionCode="1"
          android:versionName="1.0">

    <uses-sdk
            android:minSdkVersion="8"
            android:targetSdkVersion="17"/>

    <application
            android:allowBackup="true"
            android:debuggable="true"
            android:icon="@drawable/ic_launcher"
            android:label="@string/app_name"
            >
        <activity
                android:name="com.example.HelloWorldProject.MyActivity"
                android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>

</manifest>