Connecting to Oracle DB on antother server

Hi, I'm trying to connect to an oracle database which is itself on antother server than php is running. on the php machine is an oracle client succesfully installed. i've tried the different functions to connect to oracle: ociplogon('user','pass'); as well as ocinlogon, both with and without the optional third parameter, where i gave the name of the entry in tnsnames.ora as well as the value of ORACLE_SID. i always got a following error message: Warning: ociplogon() [function.ociplogon]: _oci_open_server: Error while trying to retrieve text for error ORA-12154 could anybody point me to the right direction, or is there somebody who has already done such a connection and could give me an example. thanks a lot... Beni ____________________________________________________________ This message may contain legally privileged or confidential information and is therefore addressed to the named persons only. The recipient should inform the sender and delete this message, if he/she is not named as addressee. The sender disclaims any and all liability for the integrity and punctuality of this message. The sender has activated an automatic virus scanning by Messagelabs, but does not guarantee the virus free transmission of this message.