Water in center tail light

My 93 Camry's center tail light panel gets water inside after it rains. I've taken it off, dried it out, and sealed the top edge (under/behind the rubber gasket) with cleat silicone. But water is still getting in. Anyone seen or solved this problem?

I will tell you how I was able to do it on my son's Neon:
When we pulled it out to investigate the water started dripping out from one spot. That is how we did it.

I hope this helps,
Sam