I've been having troubles with using Invitrogen's MagicMark XP Western Protein Standard. It seems that standard never appears when developing a chemiluminescent blot, even though all my samples do. No standard bands appear with a Ponceau S stain either. Only staining an extra standard with coomasie overnight shows any hint of bands. I've tried transblotting at 30 V overnight, 70 V for 4 hours, using different concentrations of standard, but nothing seems to work. My transfer buffer is 0.025 M Tris, 0.192 M Glycine, and 20 % MeOH, pH 8.3. Has anyone seen anything like this?