android - ListActivity layout not having margins around -

edit: problem seems with:

requestwindowfeature(window.feature_indeterminate_progress); 

within oncreate... don't know why...

i have code:

public class bluetoothdiscovery extends listactivity {  @override protected void onlistitemclick(listview l, view v, int position, long id) {     string mac = this.discoveredprinters.get(position);     intent = new intent();     i.putextra("mac", mac);     setresult(result_ok, i);      // finalizamos el activity     finish(); }  private arraylist<string> discoveredprinters = null; private arrayadapter<string> marrayadapter; private static discoveryhandler btdiscoveryhandler = null;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      requestwindowfeature(window.feature_indeterminate_progress);      // configuramos el theme del activity     utils.setcustomtheme(this, getapplicationcontext(), true);              setcontentview(r.layout.discovery_results);     --- 

the layout xml file follows:

<?xml version="1.0" encoding="utf-8"?> <linearlayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:gravity="center" >    <listview     android:id="@android:id/list"     android:layout_width="fill_parent"     android:layout_height="match_parent"      android:layout_margin="10dp"/>  <textview     android:id="@id/android:empty"     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:text="no printers found"      android:layout_margin="10dp"/> 

but cannot see why title close borders of activity. in case necessary, manifest expresses activity way:

    <activity         android:name=".printing.bluetoothdiscovery"         android:screenorientation="landscape"         android:theme="@android:style/theme.holo"         android:windowsoftinputmode="adjustpan|statehidden" >     </activity> 

this how activity invoked preferences:

public class adjustmentsactivity extends preferenceactivity implements     onsharedpreferencechangelistener {  .... ....      etprinter = (preference) findpreference("key_select_printer");     etprinter.setonpreferenceclicklistener(new onpreferenceclicklistener() {         public boolean onpreferenceclick(preference preference) {              string printermac = utils                     .obtenermacprintersharedpreferences(getapplicationcontext());              intent intentlocateprinter = new intent(                     getapplicationcontext(), bluetoothdiscovery.class);              intentlocateprinter.putextra("titulo",                     "búsqueda de impresora bluetooth");              startactivityforresult(intentlocateprinter,                     request_selected_printer);              return true;         }     }); 

and next visually obtain weird due lack of margings around whole view. question problem located (manifest, xml, class)?.

thanks in advance,

jose.