HTTP/1.1 500 Internal Server Error Date: Sat, 25 May 2013 10:03:33 GMT Server: CL-HTTP/70.217 (LispWorks; 2.1.7) Connection: close Content-Type: text/html; charset=ISO-8859-1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html lang="en" dir="ltr"> <head> <meta http-equiv="Content-Style-Type" content="text/css"> <link rel="stylesheet" type="text/css" href="/cl-http/css/base.css"> <title>Internal Server Error

NIL fell through ETYPECASE expression.
Wanted one of (STRING FUNCTION).