I used the SMARCD3 Antibody from Proteintech (12838-1-AP) on FFPE material (prostate), and observed a strong brown background all over the glass slides , right after the application of AEC.

Using the same staining conditions (AR: pH 9, 10 min 3% H2O2 digestion, AB diluent with 0,5% TritonX, 1% FCS in PBS, incubation o/n on 4°C, UltraVision LP AEC detection system from Thermo fisher, BIOTIN FREE!!) I had no problems with SMARCD1 and SMARCD2 antibodies on the same slides.

Have you ever seen something similar?

All the best, and thanks for help!!!