How to call NetUserModalsGet() from C#.NET?

EDIT: followup at NetUserModalsGet() returns strings incorrectly for C#.NET

I'm struggling with the DLL declarations for this function:

NET_API_STATUS NetUserModalsGet(
  __in   LPCWSTR servername,
  __in   DWORD level,
  __out  LPBY开发者_StackOverflow中文版TE *bufptr
);

(Reference: http://msdn.microsoft.com/en-us/library/aa370656%28VS.85%29.aspx)

I tried this:

private string BArrayToString(byte[] myArray)
{
    string retVal = "";
    if (myArray == null)
        retVal = "Null";
    else
    {
        foreach (byte myByte in myArray)
        {
            retVal += myByte.ToString("X2");
        }
    }
    return retVal;
}

...

[DllImport("netapi32.dll")]
public static extern int NetUserModalsGet(
  string servername,
  int level,
  out byte[] bufptr
);

[DllImport("netapi32.dll")]
public static extern int NetApiBufferFree(
  byte[] bufptr
);

...

int retVal;
byte[] myBuf;

retVal = NetUserModalsGet("\\\\" + tbHost.Text, 0, out myBuf);
myResults.Text += String.Format("retVal={0}\nBuffer={1}\n", retVal, BArrayToString(myBuf));
retVal = NetApiBufferFree(myBuf);

I get a return value of 1231 (Network Location cannot be reached) no matter if I use an IP address or a NetBIOS name of a machine that's undoubtedly online, or even my own. On edit: this happens even if I don't put a "\\" in front of the hostname.

I'm doing things wrong, I know, and let's not even get started on how to declare that blasted return buffer (which can have a number of different lengths, ewww).

From pinvoke.net (they also have some sample code on how to use it):

   [DllImport("netapi32.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall, SetLastError = true)]
    static extern uint NetUserModalsGet(
        string server,
        int level,
        out IntPtr BufPtr);

It would be better to use System.Text.Encoding.ASCII.GetBytes(somestring_param) and System.Text.Encoding.ASCII.GetString(byte_array) instead of your own routine BArrayToString.

Hope this helps.