glue plastic to metal?

I have a 2000 silverado and the bedliner attached to the gate is coming off, ive tried lots of "super glue" and they stick but not forever. I tried a brand of epoxy but it did not work and after close examination of the product it was for "school and projects"

my question is , what kind of material can i use to "glue" the plastic ( assuming its plastic bedliner) to the metal

I am not willing to rip it off and use a spray on bed liner ( as i was told by the hardware store trying to make a buck) I just want a nice type of glue product that will withstand the weather even if i have to reapply it eventually , i want it to hold for as long as it can

let me know what you recommendd if you personally know it has worked for you

I posted this under auto but also figure i can try another area as well