CTE query doesn't print the right structure?
You need to include the parentID and the childIDin the path. So instead of

RIGHT('00000' + CAST(Tbl.siblingOrder AS VARCHAR(6)), 6)


you should write 

RIGHT('0000000000' + CAST(Tbl.parentID AS VARCHAR(10)), 10) + RIGHT('00000' + CAST(Tbl.siblingOrder AS VARCHAR(6)), 6) + RIGHT('0000000000' + CAST(Tbl.childID AS VARCHAR(10)), 10)


(That is in two places in your code)

Used this way you can provide the siblingOrder where desired. If present it will override the child order. If not present the children will be ordered by their childID.

SQL Fiddle without siblingOrder

MS SQL Server 2008 Schema Setup:

CREATE TABLE dbo.MyTable
    ([childID] int, [parentID] int, [NAME] varchar(3), [siblingOrder] int)
;

INSERT INTO dbo.MyTable
    ([childID], [parentID], [NAME], [siblingOrder])
VALUES
    (1, 1, 'a', 0),
    (212, 1, 'ab', 0),
    (112, 1, 'ac', 0),
    (412, 1, 'ad', 0),
    (-912, 112, 'aca', 0)
;


Query 1:

;WITH CTE AS(
   SELECT childID, parentID, 0 AS depth, NAME , siblingOrder,
         CAST(RIGHT('0000000000' + CAST(parentID AS VARCHAR(10)), 10) + RIGHT('00000' + CAST(siblingOrder AS VARCHAR(6)), 6)+ RIGHT('0000000000' + CAST(childID AS VARCHAR(10)), 10)  AS VARCHAR(1024))  AS PATH
   FROM   dbo.MyTable 
   WHERE   childID = parentID 
    UNION ALL
    SELECT  TBL.childID, TBL.parentID,
           CTE.depth + 1 , TBL.name ,TBL.siblingOrder,
           CAST(cte.Path + '.' + RIGHT('0000000000' + CAST(Tbl.parentID AS VARCHAR(10)), 10) + RIGHT('00000' + CAST(Tbl.siblingOrder AS VARCHAR(6)), 6)+ RIGHT('0000000000' + CAST(Tbl.childID AS VARCHAR(10)), 10) AS VARCHAR(1024) )
    FROM   dbo.MyTable AS TBL
            INNER JOIN CTE  ON  TBL.parentID = CTE.childID
    WHERE   TBL.childID&lt;&gt;TBL.parentID
)
SELECT path,depth, childID, parentID, siblingOrder, REPLICATE('----', depth) + name
FROM CTE
  ORDER BY PATH


Results:

|                                                                             PATH | DEPTH | CHILDID | PARENTID | SIBLINGORDER |    COLUMN_5 |
----------------------------------------------------------------------------------------------------------------------------------------------
|                                                       00000000010000000000000001 |     0 |       1 |        1 |            0 |           a |
|                            00000000010000000000000001.00000000010000000000000112 |     1 |     112 |        1 |            0 |      ----ac |
| 00000000010000000000000001.00000000010000000000000112.0000000112000000000000-912 |     2 |    -912 |      112 |            0 | --------aca |
|                            00000000010000000000000001.00000000010000000000000212 |     1 |     212 |        1 |            0 |      ----ab |
|                            00000000010000000000000001.00000000010000000000000412 |     1 |     412 |        1 |            0 |      ----ad |




SQL Fiddle with siblingOrder

MS SQL Server 2008 Schema Setup:

CREATE TABLE dbo.MyTable
    ([childID] int, [parentID] int, [NAME] varchar(3), [siblingOrder] int)
;

INSERT INTO dbo.MyTable
    ([childID], [parentID], [NAME], [siblingOrder])
VALUES
    (1, 1, 'a', 0),
    (212, 1, 'ab', 1),
    (112, 1, 'ac', 3),
    (412, 1, 'ad', 2),
    (-912, 112, 'aca', 0)
;


Query 1:

;WITH CTE AS(
   SELECT childID, parentID, 0 AS depth, NAME , siblingOrder,
         CAST(RIGHT('0000000000' + CAST(parentID AS VARCHAR(10)), 10) + RIGHT('00000' + CAST(siblingOrder AS VARCHAR(6)), 6)+ RIGHT('0000000000' + CAST(childID AS VARCHAR(10)), 10)  AS VARCHAR(1024))  AS PATH
   FROM   dbo.MyTable 
   WHERE   childID = parentID 
    UNION ALL
    SELECT  TBL.childID, TBL.parentID,
           CTE.depth + 1 , TBL.name ,TBL.siblingOrder,
           CAST(cte.Path + '.' + RIGHT('0000000000' + CAST(Tbl.parentID AS VARCHAR(10)), 10) + RIGHT('00000' + CAST(Tbl.siblingOrder AS VARCHAR(6)), 6)+ RIGHT('0000000000' + CAST(Tbl.childID AS VARCHAR(10)), 10) AS VARCHAR(1024) )
    FROM   dbo.MyTable AS TBL
            INNER JOIN CTE  ON  TBL.parentID = CTE.childID
    WHERE   TBL.childID&lt;&gt;TBL.parentID
)
SELECT path,depth, childID, parentID, siblingOrder, REPLICATE('----', depth) + name
FROM CTE
  ORDER BY PATH


Results:

|                                                                             PATH | DEPTH | CHILDID | PARENTID | SIBLINGORDER |    COLUMN_5 |
----------------------------------------------------------------------------------------------------------------------------------------------
|                                                       00000000010000000000000001 |     0 |       1 |        1 |            0 |           a |
|                            00000000010000000000000001.00000000010000010000000212 |     1 |     212 |        1 |            1 |      ----ab |
|                            00000000010000000000000001.00000000010000020000000412 |     1 |     412 |        1 |            2 |      ----ad |
|                            00000000010000000000000001.00000000010000030000000112 |     1 |     112 |        1 |            3 |      ----ac |
| 00000000010000000000000001.00000000010000030000000112.0000000112000000000000-912 |     2 |    -912 |      112 |            0 | --------aca |