struts question: No bean specified

[Trey Howard <trey.howard@xxxxxxxxxxxxxxxx>]

Hi All

I'm working on a Struts application and just ran across a rather 
unhelpful error message:
java.lang.IllegalArgumentException: No bean specified
       at 
org.apache.commons.beanutils.PropertyUtils.getPropertyDescriptor(PropertyUtils.java:837)
       at 
org.apache.commons.beanutils.BeanUtils.setProperty(BeanUtils.java:934)
... (none of my code specified in the stack trace)

I have a JSP that submits to a servlet.
I'm pretty sure I have all my xdoclet/struts-config elements defined.
The JSP renders just fine, but when I submit any of the forms on the JSP 
(all point to the same servlet), I get the above exception.
I tried putting a debug statement at the first line of the servlet's 
execute() method, but that didn't print out.

What are common causes for encountering this exception?
Any help would be appreciated.

-Trey