It seems I have a problem with RPG Maker XP (don't think it's Essentials' issue).
The "Call Script" window appears to be too small to put a correct script line into it. When I used to use WinXP it worked fine, now on Win7 it remains small (even though the program itself works fine with no errors). Now when the script is separated in two lines the program brings and error during a gameplay.
That's not an Essentials issue. You can't cut a line of code like that. You either have to put the line break immediately after an opening parenthesis or a comma, or run the program "ExtendText.exe" in the game folder so that the window will be larger.