http-500: oracle.ias.repository.schema.SchemaException

If a Single Sign On enabled Forms server fails to perform SSO, and the client gets a http-500 error, with the stack trace below, then check your variables "oid_formsid" and "formsid_group_dn" in formsweb.cfg ($ORACLE_HOME/forms/server/formsweb.cfg)

oracle.forms.net.ConnectionException: oracle.ias.repository.schema.SchemaException:
Unable to connect to Oracle Internet Directory Server.
Please verify that the correct Oracle Internet Directory Server parameters are specified in [Oracle Home of your server]/config/ias.properties.
Make sure that the Oracle Internet Directory Server specified in OIDhost, OIDport is up and running.
Base Exception : javax.naming.NamingException: [LDAP: error code 1 - User does not exist in directory for Proxy Switch]
at oracle.forms.servlet.FormsOIDContext.getOIDContext(Unknown Source)
at oracle.forms.servlet.FormsServlet.doRequest(Unknown Source)
at oracle.forms.servlet.FormsServlet.doGet(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)