Syntax error in SQL Server Function

I'm pretty new to SQL, especially creating SQL Funcitons. I getting a syntax error when I try to compile this function in the SSMS.

USE [JTSConversion]
GO
/****** Object:  UserDefinedFunction [dbo].[isALetter]   Script Date: 2/2/2018 2:30:26 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO


Create FUNCTION [dbo].[isALetter] (@passedString varchar (1)) 
					RETURNS varchar(1)
AS
BEGIN
	-- Declare the return variable here
	DECLARE @Answer   varchar(1)
	DECLARE @strUCase varchar(1)

	set @Answer='N'    -- false

	Set @strUCase = upper(@passedString)

If @strUCase = ‘A’ Or @strUCase = ‘B’ Or @strUCase = ‘C’ Or @strUCase = ‘D’ Or @strUCase = ‘E’ Or 
   @strUCase = ‘F’ Or @strUCase = ‘G’ Or @strUCase = ‘H’ Or @strUCase = ‘I’ Or @strUCase = ‘J’ Or 
   @strUCase = ‘K’ Or @strUCase = ‘L’ Or @strUCase = ‘M’ Or @strUCase = ‘N’ Or @strUCase = ‘O’ Or 
   @strUCase = ‘P’ Or @strUCase = ‘Q’ Or @strUCase = ‘R’ Or @strUCase = ‘S’ Or @strUCase = ‘T’ Or 
   @strUCase = ‘U’ Or @strUCase = ‘V’ Or @strUCase = ‘W’ Or @strUCase = ‘X’ Or @strUCase = ‘Y’ Or 
   @strUCase = ‘Z’ 
    set @Answer='Y'

	return @Answer

END

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The error is:

Msg 102, Level 15, State 1, Procedure isALetter, Line 22
Incorrect syntax near '‘'.

Line 22 is
If @strUCase = ‘A’ Or @strUCase = ‘B’ Or @strUCase = ‘C’ Or @strUCase = ‘D’ Or @strUCase = ‘E’ Or

I don't see it.  Can anyone spot the syntax error?