Trouble Bleeding Rear Brakes, Rear left one is fine but nothing comes out of rear right Options

[LTom]

I recently overhauled both rear calipers and now i've put them back on they require bleeding. With the help of a friend who did the pedal pushing I first bled the rear left (passenger, uk) caliper which went fine. However the rear right one just will not bleed. Nothing comes out as far as I can tell, not even air. I have taken the bleed nipple off and it is not obstructed, i can blow air through it. What the hell is causing this? I'd really appreciate some help as the weather is grim and my only other means of transportation is a motorbike.

[LTom]

UPDATE: Problem solved

I opened both the rear bleed valves (with tubes on both going into jars of brake fluid) and left it like that for a few hours after which (with both sides open) I pumped the brakes for a few minutes.

When I tried bleeding the rear right valve on its own after this, bubbles did start to come out (whereas they weren't before). There was a LOT of air in the system and it took a long time for me to bleed each side properly but all is now well and my car is back on the road. For some reason having both sides open and pumping fixed the issue.

Thanks for all your help, I'm sure most of you think I'm a bit slow or doing something wrong and all I can say is that I would think the same in your position but there really was nothing coming out of that right side for a LONG time. I'm posting this update just in case someone has the same problem one day.

Merry Christmas/Happy Holidays/End of the world