Error in refering to subautomatons parts

The first rule below compiles and works as expected while the second one fails to compile wih the message `trying to get a subpart in a unit element`. The second rule compiles and works as needed when replacing `right.1.3` by `right.3`. This is false and unexpected.

```
define subautomaton NounGroup {
pattern=$DET? (@Adverb{0-2} @Adj|@Substantif|@ConjCoord|@Participe|@DetNum|@PrepComp){0-n} @Substantif
}

@Copule:@OpenQuot %NounGroup (@Adj){0-n} @ClosQuot:(@Adverb){0-2} @PastParticiple:SYNTACTIC_RELATION:
+!GovernorOf(left.1,"ANY")
+SecondUngovernedBy(left.2.3,right.2,"ANY")
+CreateRelationBetween(left.2.3,right.2,"SUJ_V")
=>AddRelationInGraph()
=AddRelationInGraph()
=