June 10th 2012, we have been getting many calls from BH owners because they have heard that we do an excellent job with the technical aspect of BHs. Today we went to district 8 in HCMC to inspect a BH that has been running for 9 months, but not even one swiftlet stays inside. When we first went in I noticed that and external sound was used instead of an internal one. Second thing was the overwhelmingly strong odor of ammonium bicarbonate. The primary hole tweeters were spliced together with the directional tweeters so only one wire came down from the top of the BH to the control room. This was a problem because the interior noise level was too loud. This Tuesday we will go back to the house and fix everything we can. Keep posted...