C# 调C++ dll文件.报:无法加载XXX.dll,找不到指定模块解决办法

        [DllImport("EncrySign.dll", EntryPoint = "GenSimpleKey")]        public static extern string GenSimpleKey(int dwLen);        private void button1_Click(object sender, EventArgs e)        {            string s =GenSimpleKey(10);            MessageBox.Show(s);        }