android - Trouble setting action bar title textAllCaps -

i'm trying set action bar title of activity caps. works if done dynamically, there's no effect when done through xml. here's code (the other attributes work normally, , size , color being set).

<style name="mainactionbartabtextstyle" parent="@android:style/textappearance.holo.widget.actionbar.title">         <item name="android:textsize">20sp</item>         <item name="android:textcolor">@android:color/white</item>         <item name="android:textallcaps">true</item>     </style> 

here's how i'm setting activity style :

<!-- main screen action bar style. -->     <style name="mainactionbarstyle" parent="@android:style/theme.devicedefault.light">         <item name="android:actionbarstyle">@style/mainactionbarbckgnd</item>         <item name="android:actionbartabtextstyle">@style/mainactionbartabtextstyle</item>     </style> 

is there possible way via xml. i've looked @ several threads on stackoverflow, none of them seems work me. i'm testing on kitkat device. appreciated.