This was counter-intuitive to me but learned it on a TD tailgate...sometimes the latch on the pillar is in too far which causes only the primary latch to engage. I found the latch had to be moved outward to get the secondary latch to engage. If you move the latch start by marking its current location and DON'T remove the screws only unsnug them and tap the latch to move it.

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer