I must of hit Sahrotaar about 15 times with "Bend Will" without success, My character is high in magic and health but not that high in stamina ,if that matters. any ideas what I'm doing wrong. This dragon is to fly me to face Miraak.

How long you hold down the R2 determines the strength of the shout. The longer the more powerful.

Hold down R2 for a good 4 or 5 secs before releasing, don't just tap it.

Have you tried reloading? What mods do you have installed?

on x-box will try holding bumper longer