light and (http://maplered.com) dark Pietra grigio spots

I have a fireplace surround make of Pietra Grigio. I seal it with ager. The finish came out blochy and (http://maplered.com) uneven light and (http://maplered.com) dark spots. The Tenax rep told me to brush the finsh and (http://maplered.com) start over putting on very light coats. I planning on going out tommow. Has anyone had this problem and (http://maplered.com) what worked.