I'm at the part where you have to dissolve the red forcefield door with six vials and then fight a zombie and a white dragon to proceed to the next area. All that I can do but for proceeding to the next area. The doorway behaves like a wall and I can find no way through. I've checked LPs/walkthroughs and can find nothing wrong with what I'm doing, nor does exiting the area to the caves seem to help (I was hoping it'd reset whatever wrong).

Does anyone know if there's some way to fix this?