Interop Error WorkBook.Open？

Question

我有这个代码在SharePoint上打开一个WorkBook，它在本地服务器上运行时效果很好但是当我远程访问时无法访问该sharepoint站点EX：

  

（本地=成功）（MachineA到SharePoint =失败）

SPSecurity.RunWithElevatedPrivileges(delegate()
{
    using (SPSite site = SPContext.Current.Site)
    {
       using (SPWeb web = SPContext.Current.Web)
       {    
          Microsoft.Office.Interop.Excel.Application app = new Microsoft.Office.Interop.Excel.Application();
          var wb = app.Workbooks;
          wb.Application.Visible = false;
          string opl = System.Security.Principal.WindowsIdentity.GetCurrent().Name.ToString();
          //The issue happens here                           
          var file = wb.Open(fileToOpen.ToString(), Missing, Missing, Missing, Missing, Missing, Missing, Missing, Missing, Missing, Missing, Missing, Missing, Missing);
       }
    }
}

我的环境是： SharePoint 2010 Windows Server 2008 Interop 14

有什么想法吗？我尝试将网络服务帐户添加到dcomcnfg中的Excel应用程序，但无论如何我使用的是使用TEST \ administrator帐户的RunWithElevatedPrivilage。