ANTLR

Anyone here a big ANTLR guy/gal?

I'm still wrapping my head around it.  I have this grammar (for IMAP):

http://fisheye.labs.jboss.com/viewrep/~raw,r=1.1/JBoss/jboss-mail/src/java/org/jboss/mail/imap4/parser/grammer.g
"6 uid SEARCH UNDELETED HEADER Message-ID 44317CD1.8000407@localhost"

I think that the problem lies here:

search [boolean isUID]
	{
		SearchCommand cmd = new SearchCommand(isUID);
     AndSearchPart part = new AndSearchPart();
     SearchPart oPart;
	}:
	SEARCH SPACE oPart =search_group[isUID] {part.addArgument(oPart);}
                 (SPACE oPart=search_group[isUID] 
{part.addArgument(oPart);})*
	{
     cmd.setPart(part);
		command = cmd;
	}
   ;

search_part [boolean isUID] returns [SearchPart part]
   {
      part = null;
   }
   :
  (part=search_part_no_arg
   |
   part=search_part_str_arg
   |
   part=search_part_num_arg
   |
   part=search_part_date_arg
   |
   part=search_part_other[isUID])
   ;

there is no search part that includes BOTH the UNDELETED (noarg) and the 
HEADER (with arg).

Am I wrong?

-Andy