connection problem between c# and USB MPI

[Zoltan]

Hi,

I tried to connect to a S7 300 with an USB MPI device. I use C# . I installed PG/PC interface 2.0.
I tried with s7online, but I get -1 as response. libnodave.openS7online("S7ONLINE")  s7online is an exist access point name.
I dont know what is the problem. :-(

Is s7online is good for me??

My code what i tried:

libnodave.daveOSserialType fds;
        libnodave.daveInterface di;
        libnodave.daveConnection dc;
        int localMPI = 3;
        int plcMPI = 2;

fds.rfd = libnodave.openS7online("S7ONLINE");
                        fds.wfd = fds.rfd;
                        if (fds.rfd > 0)
                        {
                            di = new libnodave.daveInterface(fds, "IF1", localMPI, libnodave.daveProtoS7online, libnodave.daveSpeed187k);
                            di.setTimeout(1000000);
                            int res = di.initAdapter();
                            if (res == 0)
                            {
                                dc = new libnodave.daveConnection(di, plcMPI, 0, 2);
                            }
                            else
                            {
                                throw new Exception("Hiba az adapterhez való kapcsolódás során!");
                            }
                        }
                        else
                        {
                            throw new Exception("Hiba a megnyitás során!");
                        }

                        if (!_Kapcsolodva)
                        {
                            int er = dc.connectPLC();
                            if (0 == er)
                            {
                                _Kapcsolodva = true;
                            }
                            else
                            {
                                dc.disconnectPLC();
                            }
                        }

I interested in every solution.
Thank you!