I called technical support at Advance. I was given 2 options:
a) try an adhesive promoter
b) use a 1/2" self-tapping screw to attach the "quarter pie" seal to the bed liner
Option "b" is NO option for me, because I don't like putting screws into stuff like that.
I am going to try option "a". I found
3M Adhesion Promoter 2262AT. Now, I just need to find out where I can buy it.