Bottle Goes Bust in 2012

Five years. One success.  That's the sad reality for my Colonial Williamsburg "bird bottle".  Only last year, the first year actually being affixed to the house, was this nest space taken -- as expected, by Carolina Wrens.  But 2012 was a different story.  At this time last year we had hatchlings.  So far this year, no nest at all, and no obvious signs of interest.  One never really knows what appeals to the birds.  I thought the combination of shady corner, protection from weather, and height would be a regular hit.  Hah!  But hope springs eternal.  Just maybe, next year...