Try adding more bac. For most peps, I use 25-40 units. For Tirz, 45 units. Only Ghk-cu stings for me. Reta doesn't sting, but I'm only at 1.5mg.
When you added Bac to the 'bad' vial, did the water get sucked in on its own? That means it's vacuum sealed and it's a good sign. I always like my...