No problem. Go back and look at the post I responded to and you will see that the post included the two points.
No, I'm not going to split the luminol hair with you. Luminol is used to reveal blood and in every US case that I've ever read about, blood is exactly what is revealed with luminol.
This from a US police lieutenant:
All luminol solutions can and do produce numerous false positive reactions. Opinions stating that a stain was blood because when he was sprayed with a luminol solution produced luminescence should be avoided!
http://www.redwop.com/technotes.asp?ID=118
So, obviously, in the US Luminol is not regarded as always revealing blood as you insinuate.
There is no debate about whether someone traipsed around with turnip juice on their feet, or whether there is turnip juice under the dead body. In Perugia, for some bizarre and inexplicable reason, luminol only detects something like turnip juice. I think the better question is why there is such an earnest effort to negate the luminol evidence.
Luminol reacts to much more than turnip juice. I don't know where you keep hearing it only reacts to that one thing.
A wide range of domestic and industrial substances that might be mistaken for haemoglobin in the forensic luminol test for blood were examined. The substances studied were in the categories of vegetable or fruit pulps and juices; domestic and commercial oils; cleaning agents; an insecticide; and various glues, paints and varnishes. A significant number of substances in each category gave luminescence intensities that were comparable with the intensities of undiluted haemoglobin, when sprayed with the standard forensic solution containing aqueous alkaline luminol and sodium perborate. In these cases the substance could be easily mistaken for blood when the luminol test is used, but in the remaining cases the luminescence intensity was so weak that it is unlikely that a false-positive test would be obtained. In a few cases the brightly emitting substance could be distinguished from blood by a small but detectable shift of the peak emission wavelength. The results indicated that particular care should be taken to avoid interferences when a crime scene is contaminated with parsnip, turnip or horseradish, and when surfaces coated with enamel paint are involved. To a lesser extent, some care should be taken when surfaces covered with terracotta or ceramic tiles, polyurethane varnishes or jute and sisal matting are involved.
http://onlinelibrary.wiley.com/doi/10.1002/bio.657/abstract