Android : custom dialog using android-support-v7appcompat

I add the library android-support-v7 appcompat on my project and now my customized dialog doesn't show the title. Why?

My file styles.xml:

 <style name="cust_dialog" parent="@style/Theme.AppCompat.Light">
        <item name="android:windowBackground">@android:color/white</item>
        <item name="android:windowNoTitle">false</item>
        <item name="android:windowTitleStyle">@style/dialog_title_style</item>
    </style>

    <style name="dialog_title_style" parent="android:Widget.TextView">
        <item name="android:background">@color/orange_logo</item>
        <item name="android:height">5dp</item>
        <item name="android:gravity">center_horizontal</item>
        <item name="android:textSize">@dimen/TextSize_title_dialog</item>
        <item name="android:textColor">@color/white</item>
    </style>