error parsing xml not well-formed (invalid token) in my manifest.xml

Here is my code:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://ift.tt/nIICcg"
    package="com.semesterproject"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.SEND_SMS"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:windowSoftInputMode="adjustResize|adjustPan"
            android:name=".MainActivity"
            android:label="@string/app_name" 
            android:screenOrientation="portrait" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

The error is shown at the start of activity tag. I changed the android:theme in the application to fullscreen then the error was generated, I did undo the changes i-e change the them to the previous theme that is shown in the code but it's still giving the error. What is causing the error, and how can I fix it?