Hello Jszei (Hungarian name by chance???),
It is a fairly simple process to change out the existing KiXtart files for your existing version. In fact, all that needs done is either you replace the current kixtart.exe with the new one or change your BATch file execution or User profile path to the new location. Of course, you should test out all your KiXtart scripts in the new version before commiting the change to the production environment.
I understand your frustration. It's hard to know where to look for the answers some times. For the most part, the manual will have all the KiXtart commands listed with a basic explanation of its use and some syntax questions. If you need to do something, but don't know how to in KiXtart, just post some "pseudo code" (plain english) and we'll try to help you build a KiXtart framework.
In my experience the learning curve is STEEP, especially for a non-programmer like myself. There are a lot of helpful people on this board. I hope you continue posting your questions. They're great for the community!! 
P.S. (oops, looks like I replied a few posts before the end of the thread. I missed some later comments.... Tee hee)
By the way, the @error command will return an error code (usually a number) that will help define why the script is having problems at that line.
P.S.S By the way, verify the spelling of ALL files and directories, just to be absolutely confident that isn't the problem.
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let the wise listen and add to their learning,
and let the discerning get guidance- Proverbs 1:5
