for sure that is right but i have seen packs with error on registergameserver.bat file if he can't create it, then i am telling him to use other pack. (if he don't know how to fix it)
This error coming from java so maybe it's not the file registergameserver.bat wrong but the java!
For sure it can be and from java of course, because the most problems come from java (wrong version).
For me i am telling him to use Java jre 6u21 and java JDK 6u21. These are the most popular and completed versions for interlude server. (That is what i use and i have no errors in C6. For other versions Gracia, Freya etc, use java JRE and JDK 7u41).