[80a middle] R’ Eliezer here rules that a congenital sterile man does perform Yebum/Chalitzah, and elsewhere it seems that he rules that this same individual does not perform Yebum/Chalitzah. Rami bar Dukiel quoting Shmuel: R’ Eliezer retracted his original ruling and holds in accordance with our current ruling (that the congenital sterile man does indeed perform Yebum/Chalitzah).
Prac-T-cal Tidbits: One should never be so arrogant/haughty as to never be able to admit that he/she is wrong. We must be able to own up to our shortcomings when we are incorrect. We should always try to be able to recognize and admit right away if we have erred.