Rear brake issue,

I need some advice on my rear brake, I have no resistance on the lever, I have tried bleeding the
Lower front valve , lots of bubbles but still no resistance on the lever. I'm using a vacuum pump. On the rear, I pumped the vacuum opened the bleed valve and nothing no fluid and the vacuum pressure didn't change? Any ideas appreciated

Are you sure the bleed valve at the rear caliper was not clogged? You can unscrew it completely and check. You can also open the bleed valve and push the pistons back into the caliper which ought to squirt fluid out of the bleeder (as a test).

You have not said what has led you to need to do the brake bleed. Air likes to hide in brake lines and will float up to the master. Once there is air in the master this can be a blighter to shift but vacuum bleeding should overcome this.

Doing a search in the search bar will bring up lots of info on this topic. To summarize, I had rear brake problems for ages with various results; until I replaced the Master Cylinder seals. It was the last piece of the jigsaw. Maybe start there?