asp.net 2.0+c# 调用dll

[Bangshuai]

serial.dll是个window32dll,在delphi下如下注册后能调用.
DiskDLLName = 'serial.dll';
procedure GetCDROMVolume(pDriver:pChar);stdcall;external DiskDLLName;
procedure GetDiskSerialNo(pDrv,pSerial:pChar);stdcall;external DiskDLLName;

我在c#中如下调用
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Runtime.InteropServices;
public partial class _Default : System.Web.UI.Page
{
[DllImport("Serial.dll")]
public static extern void GetCDROMVolume(out string pDriver);

protected void Page_Load(object sender, EventArgs e)
{
string pDriver;
GetCDROMVolume(out pDriver);
Response.Write(pDriver);

}
}
报错如下:无法加载 DLL“C:\Documents and Settings\Administrator\My Documents\Visual Studio 2005\WebSites\WebSite1\Bin\Serial.dll”: 找不到指定的模块。 (异常来自 HRESULT:0x8007007E)。
为什么,请帮助??

[蝶恋花雨]

是不是没在下面引用！
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Runtime.InteropServices;
例如using serial

[zhqs1000]

添加引用

[Glen_qiu]

路径不对