[plt-scheme] Case-sensitive R5RS

I want to use R5RS with rebinding and a case-sensitive reader. I'm  
using "plt-r5rs --no-prim" with the following:

(#%require (only-in scheme read-case-sensitive))
(read-case-sensitive #t)

However, the compiler complains "only-in: bad module path in: (only-in  
scheme read-case-sensitive)". This is with 4.1.

I'd be very grateful if someone would point out what I'm doing wrong.

Regards,

Alan
-- 
Alan Watson
http://www.alan-watson.org/