Three towel rads - No heat in one

Folks,

I have three towel rads in the house. Heat is travelling ok to the rads manifold and two of the towel rads are heating no problem. There is zero heat in the third & furthest from the manifold. I have bled it and its purged of air so stumped as to what to try next. Any suggestions welcome. Thanks in advance.

try closing off the valves if yu can to the good / hot ones and then see will the cold one heat up?

Check individual regulating valves on both flow and return manifolds making sure that they are all open.