急，求大神帮帮忙，关于C#调用delphi的dll文件抛错问题

Question

[DllImport(_fileDll, EntryPoint = "JX102R_Read_Card",
CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
public static extern int JX102R_Read_Card(ref int ReaderNo, ref StringBuilder CardNo, ref StringBuilder clientIP);

int readerNo = 0;
StringBuilder cardNo = new StringBuilder();
StringBuilder clientIP = new StringBuilder();
int num = JX102R_Read_Card(ref readerNo, ref cardNo, ref clientIP);

调用的时候抛错：C# 尝试读取或写入受保护的内存。这通常指示其他内存已损坏。

在Pb上面是能成功调用的

Answer 1

http://bbs.csdn.net/topics/370255271