LDAP NamingException while getting attributes

javax.naming.NamingException: [LDAP: error code 1 - 000020D6: SvcErr:
DSID-031006CC, problem 5012 (DIR_ERROR), data 0

I am able to bind fine with my active directory server, but when I try
to get any attributeu, I get the above error. I need to get the
givenName and sn. I think I am proving the wrong context?

CODE:
String ldap_search_context ="OU=users,DC=mycompany,DC=com";
String attlist[] = {"sn"}
  try
               {
              DirContext ctx = new InitialDirContext(env);
           NamingEnumeration answer = null;
           System.out.println("Connection toString: " + ctx.toString());
           Attributes matchAttrs = new BasicAttributes(true);
           matchAttrs.put(new BasicAttribute("cn","username"));
          System.out.println(matchAttrs.toString());
          answer = ctx.search(ldap_search_context, matchAttrs,attlist);
                         while(answer.hasMore())
                        {
                      SearchResult sr = (SearchResult)answer.next();
                     System.out.println(">>>" + sr.getName());

                         }

                 }