C#asp.net中遇到的问题，程序如下：
[WebMethod]
public byte[] GetPlugIn()
{
string appPath=environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles)+"\\TimeSheet";
FileStream appStream=File.Open(appPath+"\\TimeSheet.dll",FileMode.Open);
.....
}
在浏览器中测试这个服务时，报错如下：
System.UnauthorizedAccessException: 对路径“C:\Program Files\TimeSheet\TimeSheet.dll”的访问被拒绝。
   at System.IO.__Error.WinIOError(Int32 errorCode, String str)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean useAsync, String msgPath, Boolean bFromProxy)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share)
   at System.IO.File.Open(String path, FileMode mode)
   at PlugInService.Service1.GetPlugIn() in c:\inetpub\wwwroot\pluginservice\service1.asmx.cs:line 65
哪位好心人帮帮忙啊
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