I am having a hard time wrapping my head around this without a dual pivot brake in front of me, but i am just going to say that if when you pull on your brake lever and the cable housing separates from the barrel adjuster where it attaches to the caliper something that is supposed to be moving is not. I feel like it might be an issue of your cable being suck somehow to the housing, be it by kinking, bent housing end, corrosion, whatever. disconnect the cable from the 5 mm hex bolt Operator mentioned and check to make sure the cable moves freely through the housing with very little friction and the housing not moving at all.