"Shock" means to superchlorinate to high levels. "Shock" is not a product. You can use any form of chlorine to "shock" a pool except trichlor pucks. As long as you add enough to raise the cl to the appropriate level based on your CYA reading, you are "shocking" the pool. Perhaps you aren't adding a large enough dose of bleach at a time to reach shock level.
If you haven't already done so, take a look at the Best Guess table in my signature below.