Character not joining

[Yukii]

So, I edited my PSP iso to create a class for Tietra and managed to put her on the first battle at Orbonne(had to switch Lavian out) and she performed well with the class I created. I wanted her to join my party at the beginning of Chapter 2(join at the same time as Ladd, Lavian and Alicia), and even though those 3 join she doesn't. Her sprite is there on the map during the whole speech, but I'm not prompted to let her join. Anyone has any idea?

PS: I Have checked the "Join after Event" box.
PS²: I had to change her sprite set to 3A(it would be Celia or Letie, can't quite remember, although an unused version) since her sprite wouldn't allow changing for the full version(without the change she would glitch).

[Yukii]

Fixed: Apparently I had misconfigured the unit ID(and that alone caused the Joining to not happen at all).
Although now I have a new problem, her sprite and portrait on the formation menu are glitched(sprite is Ramza Chapter 1 and portrait is Letie). Unfortunately, I cannot edit the formation sprite/portrait because the edition program does not show the sprite slot(it shows the 3A slot, but is used by the bard sprite).