TableView is not refreshing the first time

TableView is not refreshing the first time

First of all, I'm sorry for my English, but I hope you'll understand what
I wan't to ask ;)
I'm creating an Iphone-App . There is a Table-View with Subjects ( like
Maths, English, etc.). When I select a row, a new TableView appears with
my grades ( A, A+, etc.). In this TableView, I can add new tests. My
problem is, when I created a test in a subject and I go back to the
Subject-TableView and go again to the subject itself (So that I can see my
individual tests), the TableView doesn't refresh every cel. So there are
cells which aren't filled, until I add a new test. Do you have any idea
what I can do? :)
Thank you very much!