Error 3251 when connecting to Oracle 8i database

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When using ADO to connect to an Oracle 8i database I get the following error

Private Sub Form_Load()
Dim cn As ADODB.Connection

Dim conn As String
conn = "uid=dave;PWD=dave;DRIVER={Microsoft ODBC For Oracle};SERVER=ora1;"

Set cn = New ADODB.Connection
With cn
.ConnectionTimeout = 30
.CommandTimeout = 30
'.Provider = "MSDASQL"
.ConnectionString = conn
.Open
.DefaultDatabase = "maximo"
End With

Text1.Text = "Connection established with " + cn.DefaultDatabase

End Sub

Can anyone help?

Thanks,

Dave