You sure SR doesn't max out at 30? Probably need to find a level 40 dark elf to see what it actually goes to with the racial skin applied...
Per LORE:
Racial Qualities:
+2 Dexterity, +2 Intelligence, +2 Charisma, -2 Constitution (ESA +2 INT, +2 CHA)
Spell Resistance of 10 + 2 / 2 levels
Darkvision
Or are you saying a spell cannot be cast on a dark elf to raise the SR above the maximum possible racial application?