i have a problem with servlets and oracle

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email: djclaux_at_hotmail.pt

Hi!
Please help me with this...
I am trying to use servlets to make a more dynamic html pages.
My servlets try to connect to a Oracle 8.

So i have a java class that trys to  conecct to the data base,
and i get this error:

java.sql.SQLException: Refused:ROR=(CODE=12505)(EMFI=4))))

the main code of this class is:



(...)

Connection connection =
DriverManager.getConnection("jdbc:oracle:thin:_at_machine:1521:DB1","system","m
anager");


(...)



and i dont know why this does not work!!!

I have installed in the machine only the ORACLE 8 Enterprise Edition
v8.0.5.0.0 for ms windows nt

Note: the database name is DB1, and it was imported sucessfully from a acess
DB with the  Oracle migration assistent for ms acess!!!

what can be wrong?
note: there is no firewall problem with that machine