Radiator Not Working

Hi All

I was wondering if I get some help. I drained the central heating system to put in a new rad. Everything was working fine, however after I had finsihed and bleed all the radiators, I find all but one Rad (not the new one) work fine. Can anyone suggest why this would be so.

Thanks
Desperate Phil :

Read FAQs no 8 and all will be revealed.

Might depend if the new radiator is a replacment with lockshield valve not balanced correctly or it's an extra radiator you've installed again with lockshield not set correctly. Meaning you've provided an easier route for the water to run.
Or if you drained down, you may have now got an air lock during re filling.
Why not close the hot ones off and see if water is then directed to the cold one.