Can't retrieve attributes from ldap

[Peter Schober]

* Erdos, Marlena <marlena_erdos at harvard.edu> [2013-01-12 00:18]:
> 18:02:23.383 - DEBUG
> [edu.internet2.middleware.shibboleth.common.attribute.resolver.provider.Shi
> bbolethAttributeResolver:119] - shibboleth.AttributeResolver resolving
> attributes for principal 1234567
[...]
> 18:02:23.474 - DEBUG
> [edu.internet2.middleware.shibboleth.common.attribute.resolver.provider.dat
> aConnector.LdapDataConnector:308] - Search filter:
> (harvardeduidnumber=$requestContext.principal)

That's odd. The former line says "principal 1234567" but the latter
line does not say "harvardeduidnumber=1234567" as I would expect here,
but has $requestContext.principal as a literal string (also my IDP has
"(uid=$requestContext.principalName)" there, so check the default
config).
If the request is in fact made with this filter it's no wonder nothing
gets returned:

> 18:02:23.735 - DEBUG [edu.vt.middleware.ldap.Ldap:195] -   filter =
> (harvardeduidnumber=$requestContext.principal)

What version of the IdP is this?
What login handler are you using?
Where is authentication configured? In the container?
-peter