c# - Selected item is null when listview looses focus -

i'm having problem listview in wpf. have:

<listview style="{dynamicresource virtualisedmetrolistview}" selecteditem="{binding selectedcode}" ....... >                 <i:interaction.triggers>                     <i:eventtrigger eventname="selectionchanged">                         <toolkit:eventtocommand command="{binding selectionchangedcommand}" passeventargstocommand="true"></toolkit:eventtocommand>                     </i:eventtrigger>                 </i:interaction.triggers>                 <listview.resources>                     <solidcolorbrush x:key="{x:static systemcolors.highlightbrushkey}" color="transparent" />                     <solidcolorbrush x:key="{x:static systemcolors.highlighttextbrushkey}" color="black" />                 </listview.resources>                 <listview.cachemode>                     <bitmapcache/>                 </listview.cachemode>                 <listview.itemcontainerstyle>                     <style targettype="{x:type listviewitem}">                         <style.triggers>                             <trigger property="iskeyboardfocuswithin" value="true">                                 <setter property="isselected" value="true"></setter>                             </trigger>                         </style.triggers>                     </style>                 </listview.itemcontainerstyle>             </listview> 

i have ribbon few buttons such as:

<fluent:ribbontabitem header="try me" visibility="visible" name="cxttab" >                 <fluent:ribbongroupbox header="general">                     <button  contenttemplate="{staticresource addnewtemplate}"/>                                         </fluent:ribbongroupbox>             </fluent:ribbontabitem> 

now, i'm using mvvm light, , have listview selecteditem binded, when click on button in ribbon selecteditem null , cannot delete item.

any idea how can mantain selecteditem when click in other elements (in case ribbon)?

thanks in advance.

delete this

 <trigger property="iskeyboardfocuswithin" value="true">                             <setter property="isselected" value="true"></setter>  </trigger>