This one has been coming up a lot lately in the forums so I figured I would post a solution here. Basically, how do you lookup a value that falls between a range in another table. LOOKUPVALUE cannot be used in this way so you have to MAXX and FILTER your way to victory!
LOOKUPVALUE Range =
VAR __Score = MAX('Table'[Score])
VAR __ID = MAX('Table'[ScaleID])
VAR __Scale =
'Scales'[ScaleID] = __ID &&
__SCore >= 'Scales'[From] &&
__Score <= 'Scales'[To]