linear layout error resource android:layout_width -

please new android apps, , following guide on android developers site, when want run code iam getting , error "no resource identifier found attribute layout_width...

here copy of xml code

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="horizontal">  <edittext android:id="@+id/edit_message"     android:layout_weight="1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:hint="@string/edit_message"/>    <button      android:layout_width="wrap_content"     android:layout_height="wrap_content"      android:text="@string/button_send" /> 

xml case sensitive. have capital ls in code, should this:

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="horizontal">      <edittext android:id="@+id/edit_message"         android:layout_weight="1"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:hint="@string/edit_message"/>      <button          android:layout_width="wrap_content"         android:layout_height="wrap_content"          android:text="@string/button_send" /> </linearlayout>