The headnote is a tad Delphic on this one:
Inaction is not giving notice for the purposes of s 104(4B).
Section 104(4B) concerns whether appeals might be treated as abandoned in certain circumstances. Where leave is granted during an appeal, section 104(4B)(b) requires notice to be given for the appeal to continue. What the unnecessarily terse and obscure headnote means is that an appeal will lapse if leave is granted unless active notice is given to the tribunal.