$oConn = new COM("ADODB.Connection");

// Data Base: ORACLE 8.0

// insert query: it works fine!!!

insert into Pact (nid,name,Apell1,Apell2,Sexo,NHisto,FNac) values (10040,'qwrwfcdf','qeqwe','qewqwe','Hombre','121217',to_date('12/12/1999','MM-DD-YYYY'))


// insert query: it does not works: php error memory

insert into Pet (NID,NPet,NPac,Diagnostico,FPet,Medico,Servicio,FPetFin,nidPass,obsPet,obsInf,codSer,itt) 
   values
   (10060,'56',10040,3,
    to_date('29-03-2001','DD-MM-YYYY'),
to_date('12-1-2001','DD-MM-YYYY,
 'oooo',
 'ttt',
 'urgencias ',
 'vv')
 

If i copy this query (generated by my php code), and paste into a SQL editor that work for make queries into data bases
and i execute it, it works fine!!!!. 

Maybe a problem of lenght?.
I hope i was wrong.