PROBLEM OCIEXECUTE WITH BOOLEAN OUTPUT PARAMETERS:

The call to the following stored procedure (oracle 8.1.7) 
from php4.2.1 (as ampache module) 
does not work with a boolean parameter.
It works fine however when I change boolean to NUMBER.

/************ the procedure in PL SQL ********************/
PROCEDURE testit(arg1 IN OUT BOOLEAN) IS
BEGIN
  arg1:=TRUE;
END;
/*********************************************************/

/************ the call from PHP **************************/
$stmt = OCIParse($connector->_connectionID, "BEGIN testit(:arg1); END;");
OCIBindByName($stmt,":arg1",$ret,10);
OCIExecute($stmt);
OCIFreeStatement($stmt);
/*********************************************************/

/************ the warning in french :-) ******************/
Warning: OCIStmtExecute: ORA-06550: Ligne 1, colonne 7 : PLS-00306: num?ro ou types d'arguments erron?s dans appel ? 'TESTIT' ORA-06550: Ligne 1, colonne 7 : PL/SQL: Statement ignored in d:\apache\htdocs\iac\test.php on line 32
false

(traduction of the warning : wrong argument number or type)
/*********************************************************/