the id is not passed to the page as a query string parameter. you should put something like this in your Where text box:
{%string.IsNullOrEmpty(QueryString.id)?"":"objectid="+ QueryString.id|(identity)GlobalAdministrator%}
.
Secondly make sure that ObjectID exists in MyTable.
P.S. If you are doing this on different objects(tables), your query is bunch of unions, but cms adds your condition each query, i.e
SELECT *
FROM (
(
SELECT null as [ObjectID], ...
FROM View_CMS_Tree_Joined AS V WITH (NOLOCK, NOEXPAND) INNER JOIN MyTable1
WHERE (objectid=1)...
)
UNION ALL
(
SELECT ObjectID as [ObjectID], ...
FROM View_CMS_Tree_Joined AS V WITH (NOLOCK, NOEXPAND) INNER JOIN MyTable2
WHERE (objectid=1)...
That might crush as well