Shen's Shadow Dash not taunting.

i just played 2 games as shen. in both game i clearly dashed though the target. the participial where there showing they where taunted. But it didn't force them to do anything they would keep moving/attacking/ using skills and items (about 50% of the time)

This may have something to do with me using Stalker's Blade, smite on them before i did the Shadow Dash.