Just had a game where Nocturne W wouldn't cast ever

where I'd spam Nocturne W before I was hit by anything by at least 1/2 a second........ yet it'd never cast. just sit there not silenced or stunned ... wwww.ww .... wwwwwwww wwwwww wwwwwwww wwwwwwwwwwww and once they were done casting spells a second or so later, then the game thought it appropriate to cast my shield lol