asp.net 中的第一个数据 api 证书创建错误

我已经从第一个数据网站下载了权限文件（"1909642928.pem"），并将其放入解决方案文件夹中。尝试从第一个数据网站下载的权限文件（"1909642928.pem"）为应用程序创建证书文件时，我收到错误：

系统找不到指定的文件。

CryptographicException ：

at System.Security.Cryptography.CryptographicException.ThrowCryptogaphicException(Int32 hr)
at System.Security.Cryptography.X509Certificates.X509Utils._QueryCertFileType(String fileName)
at System.Security.Cryptography.X509Certificates.X509Certificate.LoadCertificateFromFile(String fileName, Object password, X509KeyStorageFlags keyStorageFlags)
at System.Security.Cryptography.X509Certificates.X509Certificate..ctor(String fileName)   at System.Security.Cryptography.X509Certificates.X509Certificate.CreateFromCertFile(String filename)
at WebApplication3._Default.Page_Load(Object sender, EventArgs e) in e:'MY_References'TestApps'App'App'Default.aspx.cs:line 20
at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e)
at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e)     
at System.Web.UI.Control.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

我收到以下行的错误：

FDGGWSApiOrderService OrderService = new FDGGWSApiOrderService();
OrderService.Url = @"https://ws.merchanttest.firstdataglobalgateway.com/fdggwsapi/services/order.wsdl";
OrderService.ClientCertificates.Add(X509Certificate.CreateFromCertFile>(("xxx.pem")));

如果我必须做更多的事情来从权限文件创建证书，请帮助我。