Retrieval Argument causes Error bounding column

[unknown]

I have a fairly complicated report, which I have no doubt
can be redone in a simpler way (please do if you have the
time!). The SQL is below, and works without a problem. The
issue I have is this is one out of 3 queries which I union
together, all returning the same data in the first 2
columns, and different data in the other 5 columns.

My plan was to union the 3 queries together with this one in
the middle. Then I would add a retrieval argument:

WHERE ab1.as_code = :As_Code

I planned to add these to all 3 queries once union'd.

However, this particular one will not accept it. The error
message I get is:

"The multi-part identifier "t4.tr_location_changed" could
not be bound"

Any help is much appreciated!

SELECT 'Column 1' = a1.as_code ,
'Column 2' = a1.as_desc ,
'Column 3' =
(
CASE
WHEN t1.tr_from_loc_id IS NULL THEN
(
CASE
WHEN
(
SELECT COUNT(t2.trace_no)
FROM trace AS t2
WHERE t2.as_id = t1.as_id AND
t2.trace_no < t1.trace_no AND
t2.tr_location_changed = 'Y'
) = 0 THEN 'Asset Created'
ELSE
(
SELECT l3.objectkey
FROM location AS l3 JOIN trace AS t3
ON l3.objectid = t3.tr_to_loc_id
WHERE t3.trace_no =
(
SELECT MAX(t4.trace_no)
FROM trace AS t4
WHERE t4.trace_no < t1.trace_no AND
t4.as_id = t1.as_id AND
t4.tr_location_changed = 'Y'
)
)
END
)
ELSE l1.objectkey
END
),
'Column 4' = l2.objectkey ,
'Column 5' = t1.tr_trace_by ,
'Column 6' = t1.ddate ,
'Column 7' = 'Location Change'
FROM assets AS a1 JOIN trace AS t1
ON a1.as_id = t1.as_id
JOIN location AS l1
ON ISNULL(t1.tr_from_loc_id, -1) = l1.objectid
JOIN location AS l2
ON ISNULL(t1.tr_to_loc_id, -1) = l2.objectid
WHERE a1.as_code = :Asset_Code <<<<<<<This line breaks
it

[unknown]

The SQL needed correcting in some other area's, but the
query is fine if you:

Un-tick 'Static Bind'
Tick 'Disable Bind'

...in the database connection properties. I've struggled to
find some meaningful description to what those options do
exactly. In my case however, the SQL then works.

I hope that is of use to somebody else.

Kind Regards,

Tommy Long