R cannot resolved ... when built xml code
<p>I create a xml file presentation_main.xml:</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" &gt;
    &lt;LinearLayout 
        android:id="@+id/top"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"        
        android:orientation="horizontal"
        &gt;

        &lt;TextView 
            android:text="..."
            android:id="@+id/txtDate"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            /&gt;
    &lt;/LinearLayout&gt;
    &lt;LinearLayout 
        android:layout_below="@id/top"
        android:layout_above="@id/bottom"                       
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_alignParentLeft="true"
        android:orientation="vertical"        
        &gt;
        &lt;ImageView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/img1"
            android:contentDescription="@string/shop"
            android:src="@drawable/ic_launcher"
            /&gt;
        &lt;ImageView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/img2"
            android:contentDescription="@string/shop"
            android:src="@drawable/ic_launcher"
            /&gt;
        &lt;ImageView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/img3"
            android:contentDescription="@string/shop"
            android:src="@drawable/ic_launcher"                     
            /&gt;
    &lt;/LinearLayout&gt;

    &lt;LinearLayout 
        android:layout_below="@id/top"
        android:layout_above="@id/bottom"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_centerHorizontal="true"
        android:orientation="vertical"        
        &gt;
        &lt;ImageView 
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:id="@+id/img4"
            android:contentDescription="@string/shop"
            android:src="@drawable/preloaderf1"
            /&gt;
    &lt;/LinearLayout&gt;
    &lt;LinearLayout 
        android:layout_below="@id/top"
        android:layout_above="@id/bottom"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_alignParentRight="true"
        android:orientation="vertical"
        &gt;
        &lt;ImageView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/img5"
            android:contentDescription="@string/shop"
            android:src="@drawable/ic_launcher"
            /&gt;
        &lt;ImageView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/img6"
            android:contentDescription="@string/shop"
            android:src="@drawable/ic_launcher"
            /&gt;
        &lt;ImageView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/img7"
            android:contentDescription="@string/shop"
            android:src="@drawable/ic_launcher"
            /&gt;
    &lt;/LinearLayout&gt;
    &lt;LinearLayout 
            android:id="@+id/bottom"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_marginBottom="20dp"
        &gt;
        &lt;TextView 
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/level"
            android:layout_marginLeft="15dp"
            android:layout_marginRight="10dp"
            android:textSize="25dp"
            /&gt;

        &lt;ProgressBar
            android:id="@+id/proBar"
            style="@android:style/Widget.ProgressBar.Horizontal"
            android:layout_width="fill_parent"
            android:layout_height="30dp" 
            android:layout_marginRight="15dp"
            android:progress="50"         
            android:max="100"
            /&gt;

    &lt;/LinearLayout&gt;
&lt;/RelativeLayout&gt;
</code></pre>

<p>what is the error ? I built >>> R cannot resolve ? </p>

<p>Layout design is as follows, </p>

<p><img src="http://i.stack.imgur.com/lwWE5.png" alt="enter image description here"></p>

<p>xml file id error ?</p>
