Missies are not working! (Grand Theft Auto: San Andreas)

In general, I play the game WITHOUT CHITS (now I'm on a bank robbery), and I had a problem even then, with the flight school - the marker was on the water ?! These are flowers! Asshole, but still I went into it) And yes, I forgot to say about the
W and Z icons in San Fiero. Missy passed, but the icons remained ?! And here again the mission does not work (there the dude has to jump from the roof into the van), and also the mission with the cop. I have not found an article on this topic. I was looking everywhere! Nowhere ... (Help please