从C#代码调用delphi DLL函数

TErrorCallback = function(Msg:PChar):byte of object;
TSaveEventCallback = function (Line:PChar; HiCode:PChar; LoCode:PChar; MobileNo:PChar):byte of object;

function InitModule(ErrorCallback:TErrorCallback; SaveEventCallback :TSaveEventCallback; MainWindowHandle:THandle; Sock_Event:integer):byte; stdcall; external 'My.dll' name 'InitModule';

function DLLSocketEvent(var msg: TMessage): byte; stdcall; external 'My.dll' name 'DLLSocketEvent';

function InitObjList(Objs: array of PChar; NumObjs: byte; Name: PChar):byte; stdcall; external 'My.dll' name 'InitObjList';

这是我的C#模拟：

class Message
{
  unsigned int msg;
  int wParam;
  int lParam;
  int result;
};
delegate byte ErrorCallbackDelegate(string msg);
delegate byte SaveEventCallbackDelegate(string line,string hiCode,string loCode,string mobileNo);

[DllImport("My.dll")]
static extern byte InitModule(ErrorCallbackDelegate errorCallback,SaveEventCallbackDelegate saveEventCallback,IntPtr mainWindowsHandle,Int32 sockEvent);

[DllImport("My.dll")]
static extern byte DllSocketEvent(Message msg);

[DllImport("My.dll")]
static extern byte InitObjList(string[] objs,byte numObjs,string name);

关键是我只尝试过InitModule方法并抛出异常：
对PInvoke函数’ProjTest！ProjTest.MyClass :: InitModule’的调用使堆栈失衡.这很可能是因为托管的PInvoke签名与非托管目标签名不匹配.检查PInvoke签名的调用约定和参数是否与目标非托管签名匹配.

请在这件事上给予我帮助.我应该如何在C#中描述这些DLL函数？