I encounter "invalid variant operation" when I code the query with
input parameter, initial load is ok but subsequent refresh of the
page will display error message, see my codes below

with IBOQuery1 do
begin
Close;
with SQL do
begin
Clear;
Add('SELECT * FROM VIEW_CATEGORIES');
Add('WHERE CATEGORY_ID = :CATEGORYID');
end;
ParamByName('CATEGORYID').AsInteger := fCategoryID;
Open;
end;

if replace by IB_Query1, then everythings work fine, but I need
IBOQuery1, I works around by building the SQL string dynamically
without the use of ParamByName.

Did anyone face the same prob. ?
Is this a bug in IBOQuery1 for ISAPI application ?
any better alternative ?