Oracle 8i Client does not work with dbTools?

I have installed Personal Oracle 8.1.5.0.0 (Server and Client) and Oracle Enterprise Manager 2.1.0.0.0. It is impossible to connect to any database in the network (7.3, 8.0.x, 8.1.x), and I get the errormessage, that ora803.dll is missing. As the name of the dll says, it should come with Oracle 8.0 Clients and not with 8.1. How can fix this problem???
Because we registered the software today, we urgently want to work with the software.
Thank you,
Claudia

Most likely you have multiple Oracle homes, and one of them is still defaulting to Oracle 8.0.3. Make sure you have your PATH environment variable containing only the new Oracle home directory.

: I have installed Personal Oracle 8.1.5.0.0 (Server and Client) and Oracle
: Enterprise Manager 2.1.0.0.0. It is impossible to connect to any database
: in the network (7.3, 8.0.x, 8.1.x), and I get the errormessage, that
: ora803.dll is missing. As the name of the dll says, it should come with
: Oracle 8.0 Clients and not with 8.1. How can fix this problem???
: Because we registered the software today, we urgently want to work with the
: software.
: Thank you,
: Claudia