Bleeder valve question number 2

[Cleve]

I have a vacuum kit for bleeding the brakes. I can hook up the hose to the bleeder valve and bubbles still come through the hose with the valve tightly turned off. This is happening on both sides on the rear brakes. I am assuming the bleeder valves are not completely closing. Has anyone experience bleeder valves that wouldn't shut off completely? The hose that came with the kit fits the valve very tightly and with close examination the bubbles are coming out of valve.
Boy these brakes seem to be a big problem.
Thanks
Cleve