I think the problem is that the admin guide is not clear enough about whether $DERBY_INSTALL should be an environment variable or not, and that this may create the situation Suresh describes with copy/paste. The text does not say that $DERBY_INSTALL is an environment variable, but it says:
"(...) $DERBY_INSTALL is the directory where you installed Derby."
Thus, based on the admin guide alone, $DERBY_INSTALL should (in my opinion) not be interpreted as an environment variable, meaning that all users (both Windows and Unix) must replace occurrences of $DERBY_INSTALL with the path to the directory in which they installed Derby. Of course, all users are free to create such an environment variable, and since $DERBY_INSTALL looks exactly like a Unix environment variable, I understand that this may cause some confusion.
In other words, I think simply changing $DERBY_INSTALL to %DERBY_INSTALL% in the example provided is not a good solution. If it is changed, some additional wording is needed to explain that it must be an environment variable if copied/pasted directly.