Nostalrius Begins - Quality wow vanilla realm (1.12)

Hi,
I just upgraded in talents tree my Power Word:Fortitude and in spell book my rank 5 Fortitude it says"increases stamina 49" and when I buff, the stamina is increased only to 43 and not to 49 as an improved Fortitude

Is it a bug or what?

Are any of you aware of this fact?

The tooltips are wrong in vanilla (retail as well), so if you base the numbers by tooltips, then you are correct.

if you are basing this by looking at your HP before and after buffing, then there might be a bug.

Nothing changes afther incrase improved power word fortitude, the talent is bugged.