请教一个内存访问出错的简单问题 (50分)

function SendMsg(Toh,Msg:string):integer;
var
  ToName: array [0..63] of WideChar;
  WMsgText: array [0..999] of WideChar;
  MsgLen, I:integer;
begin
  for I := 0 to 63 do ToName[i] := #0;
  for I := 0 to 999 do WMsgText[i] := #0;
  StringToWideChar(Toh, ToName, 64);
  StringToWideChar(Msg, WMsgText, 1000);
//  MsgLen := Length(Msg);
  Result:=NetMessageBufferSend(nil,ToName,nil,@WMsgText,MsgLen);
end;

NET_API_STATUS NetMessageBufferSend(
    LPTSTR servername,	
    LPTSTR msgname,	
    LPTSTR fromname,	
    LPBYTE buf,	
    DWORD buflen	
   );

function SendMsg(Toh,Msg:string):integer;
var
  ToName, WMsgText: PWideChar;
  MsgLen, pLen: Integer;
begin
  pLen := Length(Msg) + 1;
  GetMem(WMsgText, pLen);
  StringToWideChar(Msg, WMsgText, pLen);
  pLen := Length(Toh) + 1;
  GetMem(Toname, pLen);
  StringToWideChar(Toh, Toname, pLen);
  MsgLen := Length(Msg);
  Result:=NetMessageBufferSend(nil,ToName,nil,@WMsgText,MsgLen);
  FreeMem(WMsgText);
  FreeMem(Toname);
end;

var
  ToName: LPTSTR;
  WMsgText: LPTSTR;
  MsgLen, I:integer;
begin
New(ToName);
New(WMsgText);
MsgLen:=Length(Msg)+1;
StrPCopy(ToName,Toh);
StrPCopy(WMsgText,Msg);
Result:=NetMessageBufferSend(nil,@ToName,nil,@WMsgText,MsgLen);
end;

NET_API_STATUS NetMessageBufferSend(
    servername:PwideChar ;	
    msgname:PwideChar ;	
    fromname:PwideChar ;	
    buf:PwideChar ;
    var buflen: Integer
   );