compare - OID comparison in IBM DB2 -

i'm trying use object oriented features of db2 first time. i've created types, typed tables , inserted data. problem can't compare user generated oids.

my type:

create type "orschema"."pojistovna_typ" as( nazev varchar(30),  cislo varchar(3)) instantiable ref using integer mode db2sql; 

my typed table:

create table "orschema"."pojistovna" of "orschema"."pojistovna_typ" (ref oid user generated); 

succesfully inserted data command:

insert "orschema"."pojistovna" (oid, nazev, cislo)   values("orschema"."pojistovna_typ"(1), 'ccc', '105'); 

but select doesn't work @ all, in ibm knowledge done same way:

select * "orschema"."pojistovna" "p" "p"."oid" = "orschema"."pojistovna_typ"(1); 

error: data types not compatible or not comparable "="

one way using cast funcion, i'm not sure if won't slow down query:

select * "orschema"."pojistovna" "p" cast("p".oid integer) = 1;