I bought this little wren house at the Farmer's Market in Kelowna 5-6 years ago. I hung it in this particular crabapple tree and not once has a wren considered it habitable. I mean, really, wrens use almost anything as a nest site.
All About Birds sums up the House Wren behaviour very well
Bubbly and energetic, just like their songs. Look for House Wrens hopping quickly through tangles and low branches and, in spring and summer, frequently pausing to deliver cheerful trilling songs.