Santa Cruz now recommends this new antibody (F-10) but I can't find a publication using this reference. I'm working on human et non human primate hypothalamus and so far, it doesn't work.
Before discarding the antibody, use it as well with a positive control slide. In the lab there are many ERa+ cell lines (uterine, mammary), or you order a positive control slide (human mammary gland, uterus, etc). It's possible that the antibody is OK but the number of receptors in the hypothalamus might be very few making detection difficult. Could be amplified with HRP conjugation, though.