wpf - Entity Framework-Getting value from navigational property -

i have 3 entities in model. a->b->c, super parent , c child. c derived b, , b derived a. loading c datagrid, , need able display values b , a. right can display values of b saying:

 dgia.itemssource = ctx.c.oftype<some_type>().include("b"); 

and in xaml say:

  <datagridtextcolumn header="property 1" binding="{binding a.name}"/>   <datagridtextcolumn header="property 2" binding="{binding b.name}"/>   <datagridtextcolumn header="property 3" binding="{binding frequency}"/>//a value in c 

i need able display a.name, if try include saying:

ctx.c.oftype<some_type>().include("b").include("a"); 

i exception:

a specified include path not valid. entitytype 'db.some_type' not declare navigation property name 'a'.

i understand why doing this, entity c has navigational property b, , b has navigational property a, want c able value in way have shown. how this? thank much!

so saying in xaml:

   <datagridtextcolumn header="property 1" binding="{binding b.a.name}"/> 

this accessed nav property of b access a.

and:

  dgia.itemssource = ctx.a.oftype<some_type>(); 

no includes or needed. apprently ef's 'relationship fix-up' handles it, need dot accessors.