weird sort order

[piti]

I'm getting not quite what i would like to from a my database and do not know why

here's the problem description:
i have data in a table, the data is some kind of a tree, with 5 levels of nesting
the structure of the data is following
- every level has its name and id (AtrName, IdAtr)
- there are 5 levels of data
- in the table, there is also the top level stored (AtrName_top, IdAtr_top)
i would like having the SELECT returning the tree like this

top1
top1 - L1(1)
top1 - L1(1) - L2(1)
top1 - L1(1) - L2(2)
top1 - L1(2)
top1 - L1(2) - L2(1)
top1 - L1(3)
top1 - L1(4) - L2(1)
top1 - L1(4) - L2(2) .....

when using code shown below, the result is not sorted in order i need it to be
i'm getting something like (the "error" is show with an *)
top1
*top1 - L1(1) - L2(1)
*top1 - L1(1)
top1 - L1(1) - L2(2)
top1 - L1(2)
top1 - L1(2) - L2(1)
top1 - L1(3)
top1 - L1(4) - L2(1)
top1 - L1(4) - L2(2) .....
only some of the returning records are not sorted properly

the code is:
SELECT * FROM Tree
ORDER BY
AtrName_top, IdAtr_top,
CASE
WHEN IdAtr_04 IS NOT NULL THEN AtrName_03
WHEN IdAtr_04 IS NOT NULL THEN IdAtr_03
WHEN IdAtr_03 IS NOT NULL THEN AtrName_02
WHEN IdAtr_03 IS NOT NULL THEN IdAtr_02
WHEN IdAtr_02 IS NOT NULL THEN AtrName_01
WHEN IdAtr_02 IS NOT NULL THEN IdAtr_01
WHEN IdAtr_01 IS NOT NULL THEN AtrName_00
WHEN IdAtr_01 IS NOT NULL THEN IdAtr_00
END,
CASE
WHEN IdAtr_04 IS NOT NULL THEN AtrName_02
WHEN IdAtr_04 IS NOT NULL THEN IdAtr_02
WHEN IdAtr_03 IS NOT NULL THEN AtrName_01
WHEN IdAtr_03 IS NOT NULL THEN IdAtr_01
WHEN IdAtr_02 IS NOT NULL THEN AtrName_00
WHEN IdAtr_02 IS NOT NULL THEN IdAtr_00
ELSE NULL
END,
CASE
WHEN IdAtr_04 IS NOT NULL THEN AtrName_01
WHEN IdAtr_04 IS NOT NULL THEN IdAtr_01
WHEN IdAtr_03 IS NOT NULL THEN AtrName_00
WHEN IdAtr_03 IS NOT NULL THEN IdAtr_00
ELSE NULL
END,
CASE
WHEN IdAtr_04 IS NOT NULL THEN AtrName_00
WHEN IdAtr_04 IS NOT NULL THEN IdAtr_00
ELSE NULL
END

anyone who knows why this happens?
plz help