If @type is declared as an INT, I don't believe you need any kind of quotes around the actual numbers you are comparing it to.

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

CREATE FUNCTION dbo.tf_Points(@Grade AS VARCHAR(10), @Type AS INT)

IF @Type = 618 or @Type = 617 BEGIN

SELECT

CASE

WHEN @Grade = 'DS*' THEN 180

WHEN @Grade = 'DS' THEN 150

WHEN @Grade = 'ME' THEN 105

WHEN @Grade = 'PA' THEN 45

WHEN @Grade = 'FL' THEN 0

ELSE NULL END

RETURN

END

ELSE