Cold radiator

[ajcormi]

Hello, I'm new here and hope someone can help. I have no real plumbing skills and have 1 cold downstairs radiator so far I have:
Replaced the valve
Bled the radiator
Hosed out the radiator (cleared out black oily stuff)
Done the bucket test (no blockage, hot water came through pipes)
One of the pipes is cold, when I turn all other radiators off this radiator gets warm but not hot
Any ideas would be gratefully received

 

[HERTS P&D]

System needs to be balanced.

Andy

 

[ajcormi]

Thank you for the quick reply
Is that something a toal novice like me could possibly do or would I need a plumber. I have a combi boiler by the way. Not sure if that makes a difference