Well, how do you do it? I know that you just have to click on the lever when the cursor turns into a glove but it doesn't always work for me. More often it doesn't work. Is this a bug or I'm doing something wrong?

You have to double-click.

Some levers require a piece of wood inserted to the hollow space on the floor, before pulling them. Some levers, like the one right next to your cell in the beginning, do not work, and unfortunately, besides this being a bug, it works as intended. Others, like the one next to the elevator, require you to solve a riddle, like getting a rope and using it on the gears; to do this, you have to pull the lid by double clicking it. Other levers, like the one at the exit of Akbaa 's temple, require you to proceed further in the story to be able to use them for opening secret passages and exits.

Do not forget to read the book, besides being the inventory/stats it also keeps notes for your progression. And if a lever is stubborn, steer clear off of it, it 's either bugged or useless. Remember to make exceptions for levers in late game, like level 6 in caves before snakewomen, or way down into the crypt. There you have to either figure puzzles, or proceed into the story to use them properly.