c# - Issue with detached binding at initialization for element not in visualtree for WPF UserControl -

i have had issue wpf of lately. properties not in visualtree have no way of getting datacontext work bindings out. provide example.

<path>   <path.data>      <combinedgeometry>        <combinedgeometry.geometry1>          <rectanglegeometry.transform>            <scaletransform scaley="{binding whatscale, converter={staticresource dosomethingawesome}, fallbackvalue=1, targetnullvalue=1}"/>          </rectanglegeometry.transform>        </combinedgeometry.geometry1>        ...      </combinedgeometry>   </path.data> </path> 

i worked out adding dummy reference object , adding source of binding

<frameworkelement x:name="dummyelement"/> ... scaley="{binding datacontext.whatscale, converter="{staticresource dosomethingawesome}", source="{x:reference dummyelement}}" 

however: still these annoying information console messages saying

bindingexpression cannot retrieve value null data item.  happen when binding detached or when binding  nullable type has no value. bindingexpression:path=datacontext.whatscale 

the usercontrol rendered itemscontrol , issue believe datacontext null when initialized , directly after set code still works. however, dont "information" get, want understand happens , how can avoid it.

thanks!