I am trying to create a paging query using CTE. It works fine when I execute it from Microsoft SQL Server Management Studio Query Editor. And the result set is perfectly sorted as I want. But when I modify it for a stored procedure it gives me a unsorted result and I don't have any clue why.

Here is my Query,

with items as
(
select ROW_NUMBER() over (order by create_time desc) number
    , i.item_name item_name
    , i.create_time create_time
    , c.category_name category_name
    , i.category_id category_id
from cb_item i, cb_category c
where i.category_id = c.category_id
and c.category_id = '4E5248FE-05DD-4D01-ABBB-80C6E3BA5CDA' 
)
select item_name
, create_time
, category_name
, category_id
from items
where number between 1 and 25

And this is the Stored Procedure Version,

    create procedure ItemPage @category_id uniqueidentifier
    , @from int
    , @to int
    , @sortby nvarchar(50)
    as
    begin
    with items as
    (
    select ROW_NUMBER() over (order by @sortby) number
        , i.item_name item_name
        , i.create_time create_time
        , c.category_name category_name
        , i.category_id category_id
    from cb_item i, cb_category c
    where i.category_id = c.category_id
    and c.category_id = @category_id 
    )
    select item_name
    , create_time
    , category_name
    , category_id
    from items
    where number between @from and @to
    end


exec itempage '4E5248FE-05DD-4D01-ABBB-80C6E3BA5CDA' , 1, 25, 'create_time desc'

The first one gives me sorted result but procedure gives me unsorted result. I don't know why?