I'm trying to add manifester progression to the Tempest PrC. I've added what I believe are the necessary lines to psi_inc_core.nss but no matter what combination of Tempest levels (or even all levels) that I assign progression to, only the second level of Tempest seems to ever add progression. This is what I added in the section that has other PrC's with manifester progression
if(GetLevelByClass(CLASS_TYPE_TEMPEST, oCreature))
{
    nLevel += GetLevelByClass(CLASS_TYPE_TEMPEST, oCreature) - 1;
         if(GetLevelByClass(CLASS_TYPE_TEMPEST, oCreature) >= 5) nLevel -= 1;
         if(GetLevelByClass(CLASS_TYPE_TEMPEST, oCreature) >= 8) nLevel -= 1;
         if(GetLevelByClass(CLASS_TYPE_TEMPEST, oCreature) >= 10) nLevel -= 1;
}

Are there any other files I need to edit?