为什么我用GetPrivateProfileString读取到的信息总是为空值?



 public class OperIni
    {
        // 声明INI文件的写操作函数 WritePrivateProfileString()

        [System.Runtime.InteropServices.DllImport("kernel32")]

        private static extern long WritePrivateProfileString(string section, string key, string val, string filePath);

        // 声明INI文件的读操作函数 GetPrivateProfileString()

        [System.Runtime.InteropServices.DllImport("kernel32")]

        private static extern int GetPrivateProfileString(string section, string key, string def, System.Text.StringBuilder retVal, int size, string filePath);


        private string sPath = null;
        public OperIni(string path)
        {
            this.sPath = path;
        }

        public void Writue(string section, string key, string value)
        {

            // section=配置节，key=键名，value=键值，path=路径

            WritePrivateProfileString(section, key, value, sPath);

        }
        public string ReadValue(string section, string key)
        {

            // 每次从ini中读取多少字节

            System.Text.StringBuilder sbValue = new System.Text.StringBuilder(255);

            // section=配置节，key=键名，temp=上面，path=路径

            long returnValue = GetPrivateProfileString(section, key, "", sbValue, 255, sPath);

            return sbValue.ToString();

        }

 


    }