Yafray Render Glass

i´m trying to use yafRay to render a glass but the glass is getting black in two spots, how can i make disappear that spots?!

A few things you could try -
It could be Normals. Edit mode - Select All - N - Recalculate Normals
Try increasing Raydepth on the Settings panel to at least 4 or 5
Enable Transparent Shadows.
ior for glass should be around 1.50, higher values can cause a more reflective surface.

Failing that try Set Smooth or add a Subsurf Modifier if you haven’t already.

(btw to save confusion, that is Yaf(a)ray, Yafray is different.)

…and welcome to blenderartists, I hope your stay here will be happy and fruitful…