i am assuming you used the form to enter data  to proposition. what is the type of data that is entered (text or numeric), Can you give and example of before and after. 

Usually when such issues have seen, we should check if the DB has support for turkish character set and Appserver jvm has correct "file.encoding" param set( check SMA->Java VM information).

do you see similar behaviour on other part of the application, where data is persisted to DB and then read back, for example description labels of rules or some text in the section rules?.

you can also run a tracer and check if you can see the correct text, that is entered into the form, in the tracer XML file. Beware that tracer xml is a text file, hence your text editor should be able to read those characters

Regards Manu