Style setting within user control vs. setting in generic.xaml

[Bob]

If we set style via  

<UserControl.Resources>
       <Helpers:RequiredValueStyleSelector x:Key="RequiredFieldStyleSelector" />
       <Style TargetType="telerik:GridViewDataColumn">
           <Setter Property="CellStyleSelector" Value="{StaticResource RequiredFieldStyleSelector}"/>
       </Style>
 </UserControl.Resources>

within our User Control
all is working as expected but if comment this in usercontrol out and put the same code

<Helpers:RequiredValueStyleSelector x:Key="RequiredFieldStyleSelector" />
<Style  TargetType="telerik:GridViewDataColumn">
    <Setter Property="CellStyleSelector" Value="{StaticResource RequiredFieldStyleSelector}"/>
</Style>

 

 into generic.xaml nothing happens

Any suggestions?
PS. in Helper.dll attributes look like

PS. in Helper.dll attributes look like

 

[assembly: ThemeInfo(
    ResourceDictionaryLocation.None,
    ResourceDictionaryLocation.SourceAssembly
    )]

 

 

 

[Bob]

Hello Telerik -Team,

I'm not sure where my question belongs so I reposted this question in general forum ( http://www.telerik.com/community/forums/wpf/general-discussions/theme-styles.aspx)

Best regrads,
bob