wpf - usercontrol datacontext different usings -

when write :

    <usercontrol>         <usercontrol.datacontext>             <loca:databindingdemo></loca:databindingdemo>         </usercontrol.datacontext>          <textbox   text="{binding path=currenttime}" height="30" background="aqua" margin="133,141,169,140"></textbox>      </usercontrol> 

with xmlns:loca="clr-namespace:myclock"

it currect , there no problem,but when write:

 <usercontrol  datacontext="{binding source=clr-namespace:myclock.databindingdemo}">         <!--         <usercontrol.datacontext>             <loca:databindingdemo></loca:databindingdemo>         </usercontrol.datacontext>         -->          <textbox   text="{binding path=currenttime}" height="30" background="aqua" margin="133,141,169,140"></textbox>      </usercontrol> 

or

    <usercontrol  datacontext="{binding  source=staticresource, path=clr-namespace:myclock.databindingdemo}">         <!--         <usercontrol.datacontext>             <loca:databindingdemo></loca:databindingdemo>         </usercontrol.datacontext>         -->          <textbox   text="{binding path=currenttime}" height="30" background="aqua" margin="133,141,169,140"></textbox>      </usercontrol> 

it not work! why?

thanks in advance.

it not work! why?

clr-namespace: used create namespace mapping custom classes , assemblies , can't used directly in markup extension, not namespace prefix.

edit: can't use local types in assembly directly in markup extension that.

first have create namespace mapping have done in question this: xmlns:local="clr-namepsace:your_assembly_name.namespace_containing_type_you_want".

then can use them in markup extensions this:

<usercontrol datacontext="{binding source=local:myclock.databindingdemo}"> //                                          ^ //                                          | //                                   notice namespace using here