try to make a rectangle and fill it with 100 65 0 20 color, ok?
then make a copy of it and add gradient transparencie tool but not from corner -- make it from center of rectangle, ok?
then try to measure color in the rectangle with transparencie in place where color must be 100% (as in the first obgekt)
have you made it?
and now the most interesting part of this...
how can you explaine what the color in place where you measured it is 80 65 0 20?!!!