What is the reason for no staining?

After staining, sections do not see any positive signal, that is, no staining, This is a relatively common phenomenon in immunohistochemistry, there are many reasons for this phenomenon, Common reasons are wrong primary antibody, inappropriate concentration(usually too low) of primary or secondary antibody, inappropriate pH of antibody diluents, Insufficient deparaffinization, insufficient antigen retrieval and the secondary antibody was not stored in the dark, etc.