Nether portal doesn’t work

I have Minecraft on the iPad, and when i create a portal to the nether, and I go in, I automatically die because "I tried to swim in lava" "I combusted" etc etc. I imagined that it was happening because the portal was in a place with lava, and that's why it died automatically, so I changed it places 3 times and nothing, it's still happening. Basically I can't access the nether please help