ORA-06401 invalid driver designator error

[Dev00059]

I have just downloaded PL/SQL developer and tried to connect to an Oracle database over the internet and get the following error ORA-06401 invalid driver designator. I know that i need SQL*NET but where do I get this, how do I install it, does it need an evironment variable etc?

Can anyone help?

 

[Marco Kalter]

Apparently you already have Oracle Net, but there is something wrong with the connect string you entered.