process communication between vb6 and c#

Hello, i have two applications (once in vb6 and once in c#) which have to communicate together. They have to send and receive strings. I used api-method sendmessage, but it doesn't work. in vb: Private Declare Function SendMessageByStr& Lib "user32" Alias "SendMessageA" _ (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal _ lParam As String) [..] Call SendMessageByStr(hwndTarget, MessageId, 4, "test") in C#: unsafe protected override void WndProc(ref Message m) { if (m.Msg == VB6_TO_CSHARP_MessageId.ToInt32()) { try { string url = new string((char*)(m.LParam.ToPointer()), 0, m.WParam.ToInt32()); } catch(Exception ex) { MessageBox.Show(ex.Message); } } base.WndProc(ref m); } There is an exception by reading string. Has anyone sourcecode to send and receive strings from VB6 and C# applications? As an example project use this from codeproject (this project only send normaly messages, no strings): http://www.codeproject.com/dotnet/VB6andVBNETWindowMessages.asp Can you help? Sincerely, Andre