PowerShell Named Pipe: no connection

I need a named pipe to read and write.

In a program I create the pipe server using from kernel32.dll:

string PipeName = "\\\\.\\pipe\\myMT4"; 
int PipeMode = PIPE_TYPE_MESSAGE|PIPE_READMODE_MESSAGE|PIPE_WAIT; # tried too: PIPE_NOWAIT
int hPipe = CreateNamedPipeW(
            PipeName,
            PIPE_ACCESS_DUPLEX,
            PipeMode,
            PIPE_UNLIMITED_INSTANCES,1024,1024,
            NMPWAIT_USE_DEFAULT_WAIT,NULL);

The handle hPipe is valid – every things seems to be ok here!

But in a PowerShell-script I want to open a client, connect and open the writer –
and cannot connect => timed out

function connect{
    Param ([PSObject] $h)
    ...
    $h.Pipe = New-Object -TypeName System.IO.Pipes.NamedPipeClientStream "\\.\pipe\PipeTest"
    $h.Pipe.Connect( 5000 )
    $h.Writer = New-Object -TypeName System.IO.StreamWriter $h.Pipe, $h.Encode 

I really would prefer this way to have a similar access when reading and writen
either from/to the pipe and sockets e.g.:

function write{
    Param ([PSObject] $h, [string] $line )
  try {
        $h.Writer.Write($line) 
    }       

What is wrong?
Thanks in advance,
Gooly.

PS:
It seems that the program cannot deal with pipe-servers – I have to open a pipe-client, and that works but that causes other problems:

I define for the PowerShell-pipe-server :

 $pipeName = "testpipe"
 $pipeDir  = [System.IO.Pipes.PipeDirection]::InOut
 $pipeMsg  = [System.IO.Pipes.PipeTransmissionMode]::Message
 $pipeOpti = [System.IO.Pipes.PipeOptions]::Asynchronous
 $pipe = New-Object system.IO.Pipes.NamedPipeServerStream( 
                  $pipeName, $pipeDir, 1, $pipeMsg, $pipeOpti )
 $pipe.WaitForConnection() # 
 $sw = new-object System.IO.StreamWriter $pipe
 $sw.AutoFlush = $true
 $sw.WriteLine("Server pid is $pid")
 $sw.Dispose()
 $pipe.Dispose()

1) My first problem is now that the powerShell-pipe-server is blocked by

 $pipe.WaitForConnection()

until a client connects but it must handle 2 different sockets independently meanwhile and

2) if the client closes the connection I was unable to tell the client to open the same pipe again and the client gets the Windows-error: ERROR_PIPE_BUSY 231

Form the program I connect to the server with the kernel32.dll-function:

 int CallNamedPipeW(string PipeName, 
           string outBuffer, int outBufferSz, 
           uint& inBuffer[], int inBufferSz, 
           int& bytesRead[], int timeOut
 );

Any ideas?