blitz silence (r) not working or working for as long as the time mentioned...

in a few games not all the time ive been experiencing enemy champions being able to use skills while silenced and hit by blitz's ultimate... mainly i see lee'sins doing it by hopping over to ally with his w I think... whats the point of blitz having an ult if it doesnt do what its meant to do.. each of these times i still see the white bar under the champion signaling that they are silenced yet they can still use skills that they dont precast before going in... please fix