Autocomplete TextBox

Question

I working in a silverlight(XAML) project  where we are using autocomplete textbox

Eg: if a word is like "Sky High"..if i starting typing as like 'sky' it is showing the word in the auto complete textbox but if I am typing as 'High' for the same word..it is not showing that particular word in the auto complete  textbox. Please anyone help in that way. Thanks in adavance.