we use cell protein (50 ug/ul) to screening a series of antibodies (..., and b-actin), the primary antibody dilution according to manufacturer's instructions. and diluted the secondary antibody by referring to previous studies... but ,here the problem is that b-actin get a standard band detected. But some of antibodies no band detected(Ikk a/b), while the size marker line detected... can anyone tell me what the problem is? thanks