สอบถามการเขียน FUNCTION ใน sql ครับ พอดีเขียนแล้วมี error ไม่รู้ว่าผิดตรงไหนช่วยแนะนำให้ด้วยครับ

ALTER FUNCTION [dbo].[Cal_All_Electricity]
( 
	@total FLOAT(53),
	@nElecCostRate FLOAT(53),
	@nServiceCost FLOAT(53),
	@nFt FLOAT(53),
	@nVat FLOAT(53),
	@nele_type FLOAT(53),
	@nfirst_unit FLOAT(53),
	@nsecond_unit FLOAT(53)
)
RETURNS FLOAT(53)
AS
BEGIN
	DECLARE @electric_base_cost FLOAT(53),
					@electric_Ft_cost FLOAT(53),
					@vat_cost FLOAT(53),
					@elecCost FLOAT(53),
					@unit1 FLOAT(53),
					@cal_nfirst FLOAT(53),
					@unit2 FLOAT(53),
					@cal_nsecond FLOAT(53),
					@cal_nexceed FLOAT(53),
					@cal_all_ele FLOAT(53),
					@cal_ft FLOAT(53),
					@cal_vat FLOAT(53),
					@cal_total_ele FLOAT(53)

IF (@nele_type = 6.1)

	SET @electric_base_cost = ((@total * @nElecCostRate) + @nServiceCost);
	SET @electric_Ft_cost = (@total * @nFt * 0.01);
	SET @vat_cost = ((@electric_base_cost + @electric_Ft_cost) * @nVat);
  SET @elecCost = (@electric_base_cost + @electric_Ft_cost + @vat_cost);
        
  RETURN @elecCost
ELSE IF (@nele_type = 1.2)
				IF(@total > 150){
            SET @unit1 = (@total - @nfirst_unit);
            SET @cal_nfirst = (@nfirst_unit * 3.2484);
        }ELSE{
            SET @cal_nfirst = (@total * 3.2484);
        }
        IF(@unit1 >= 250){
            SET @unit2 = (@unit1 - @nsecond_unit);
            SET @cal_nsecond = (@nsecond_unit * 4.2218);
        }ELSE{
            SET @cal_nsecond = (@unit1 * 4.2218);
        }
        IF(@unit2 >= 1){
            SET @cal_nexceed = (@unit2 * 4.4217);
        }
	SET @cal_all_ele = (@cal_nfirst + @cal_nsecond + @cal_nexceed + @nServiceCost);
	SET @cal_ft = (@total * (@nFt/100));
	SET @cal_vat = ((@cal_all_ele + @cal_ft) * @nVat);
	SET @cal_total_ele = (@cal_all_ele + @cal_ft + @cal_vat);

  RETURN @cal_total_ele
END