The documentation in "2.23 Keyword RAISE" mistakingly states in the usercondition section that that usercondition can be a literal string or a symbol.
It must not be a literal string, but can be a string value not only a symbol (according to ANSI/INCITS a symbol, serving as a name e.g. for variables, is more restricted than a string value) here is the error text:
19 *-* RAISE USER "something RAIS-ed! " /* everything o.k., yet raising ... */
Error 20 running E:\rony\Projekte\Buchprojekte\ooRexx_2012\BP1\code\a1\b_routine_02b.rex line 19: Symbol expected
Error 20.915: Symbol expected after USER keyword