i had the same problem - the error in your procedure is the TNS-name:
i took this syntax for the tns:
($conn = Ora_Logon("<user>@(DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(Host = <hostname>)(Port = <port>)))(CONNECT_DATA = (SID = <oracle_sid>)))","<pswd>"))
.... and it runs g
