The word @drawable is not correctly spelled

I have a styles.xml file with the following in it:

<style name="Theme.MyApp" parent="android:style/Theme.Holo">
    <item name="android:actionBarStyle">@style/ActionBar</item>
</style>

<style name="ActionBar" parent="android:style/Widget.Holo.ActionBar">
    <item name="android:background">@drawable/actionbar_b</item>
</style>

I get the error The @drawable is not correctly spelled'.actionbar_b' file is on its place.