Working on fitting a vintage bike with some non-aero brake levers + vintage calipers. Calipers + levers are installed but I don't seem to be able to get the tension in the cable - it stays for a second but then the cable seems to "pop" at the lever end. I pulled the cable as tight as it will go through the caliper and fit the cable through the hole in the brake lever so the bigger side of the hole is facing the ground (smaller side of hole facing rider). I also have the housing on right now.

Any suggestions?