ND and UV filter OK, pole filter strong vignetting

I have it set this for both my 16-50 mm 2.8 lens with 72mm filter thread as well as my 18-200 mm 3.5 - he purchased 6.3 lens with 62mm filter thread. I can not say anything negative about the ND8 and the UV filter, but the polarizing filter is not what I had hoped for. I have almost all zoom levels in both lenses a strong vignetting in the corners. Too bad that detracts from the joy of this set being too. Otherwise, I must say, a great bag for the filter and the cleaning cloth. but only 3 stars because I personally consider because of the pole filter for it unusable.