Dax formula help

-- This measure returns a color when only
-- one record type and one student group
-- is visible in the current context

[Student Group Color] =
var __studentGroup = SELECTEDVALUE( MyTable[StudentGrp] )
var __oneStudentGroupVisible = HASONEVALUE( MyTable[StudentGrp] )
var __oneRecordTypeVisible = HASONEVALUE( MyTable[RecordType] )
var __shouldDisplay =
	__oneStudentGroupVisible && __oneRecordTypeVisible  
var __recordType = SELECTEDVALUE( MyTable[RecordType] )
var __avgdfs = SELECTEDVALUE( MyTable[AvgDFS] )
var __allStudentsAvgdfs =
	CALCULATE(
		MAX( MyTable[AvgDFS] );
		MyTable[RecordType] = __recordType,
		MyTable[StudentGrp] = "All Students",
		ALL( MyTable )
	)
var __color =
	switch( true(),
		__studentGroup <> "All Students",
			if(__avgdfs > __allStudentsAvgdfs, "Green", "Red"),
		__studentGroup = "All Students",
			"Yellow"
	)
return
	if( __shouldDisplay, __color )