Hi to whom may concern...
I got Frustrated with my continue failure to process my charts correctly, I don't know why after a long time spent study and my result isn't accurate with the correct answers.
It's normal or it going to be a failure in the real exam?

First, this stuff is step 1; step 2 and so on. You will get on top of it before too long.

Second, we can't offer assistance unless we can see what you are doing. How about you run a couple of examples, scan them, and post them to the thread ? Then we will be cooking with gas and you will sort out your problem very quickly.