Are you pulling in the front brake lever to ensure no air is trapped at the master cylinder? You need to pressurize the vac, then release the bleed valve and keep pumping while fluid/air is pulled into the vac container. Once it's just fluid coming out tighten the bleed valve shut and do the other side. Do the left caliper first, then the right. You might need to do each a couple times. Make sure you pull in the front brake lever a few times to get all air out of the master. The total process should take no longer than 10 minutes start to finish. Also, while bleeding the calipers carefully monitor the reservoir to ensure it doesn't run low on brake fluid or you'll end up just sucking air back into the lines.