I am having an argument with one of my players about the effects of Burning Blood from the Spell Compendium and energy immunity.

Specifically if a hypothetical creature has immunity/resistance enough to both Fire and Acid to completely ignore the damage from the spell. 

Would the creature still have to make a fortitude to deal with the Searing Pain secondary effect? or would the creature simply ignore it since it takes no damage and would not need to make a save as such?