Autonumber identity sql server แบบมี format ORYY0001 ติด error ตอน Insert

create function NextOrderNumber()
returns char(8)
as
begin
        declare @lastval char(8)
        declare @curyear char(4)
        set @curyear = 'OR' + (select right(YEAR(getdate()),2))
        set @lastval = (select MAX(orderNumber) from [PROJ].[dbo].[ZTemp001] where orderNumber like '%' + @curyear + '%')
        if @lastval is null set @lastval = (@curyear + '0000')
        declare @i int
        set @i = convert(integer,RIGHT(@lastval,4)) + 1
        return @curyear + right('000' + convert(varchar(10),@i),4)        
end