Problem with sentences in scriptcase

I have a problem. I have a grid with a list of requests, those requests can be in 3 states (Accepted, Rejected, Waiting). I also have 3 user groups (Administrator, Employee, Supervisor). Well, my problem is that I want the "technical" user that is in the "Supervisor" group to only see the requests that are "On Hold". In the login application I put the following statement to save it in a global variable called [usr_group]:

$sql2 = "SELECT group_id FROM sec_users_groups";
sc_lookup(gu, $sql2);
$usr_group = {gu[0][0]};
sc_set_global($usr_group);

In the request grid I have put the following SQL statement:

SELECT
PK_SOLICITUD,
FK_EMPLEADO,
FECHA_SOLICITUD,
FECHA_INICIO,
FECHA_FIN,
FK_MOTIVO,
FK_ESTADO,
JUSTIFICANTE,
DOCUMENTO,
N_DIASSOLICITADOS,
FK_TIPO
FROM
solicitud
WHERE
FK_EMPLEADO='[usr_login]'
OR
'[usr_login]'='admin'
OR
'[usr_group]'= 3
AND
FK_ESTADO = 3

The problem is that the user who is in the "Supervisor" group, sees the ones that are "On Hold" but the others too. What could be the problem?

Thank you!