title: C#, Unable to import .p7b certificate to windows store
body: <p>I'm trying to import certificate (smime) with extension .p7b to windows store.</p>
  
  <p>This is the current code</p>
  
  <pre><code>X509Certificate2 cert = new X509Certificate2(@"C:\test_public_cert.p7b");
  X509Store store = new X509Store(StoreName.AddressBook, StoreLocation.LocalMachine);
  store.Open(OpenFlags.ReadWrite);
  store.Add(cert);
  </code></pre>
  
  <p>It gave me an error that "Cannot find the original signer".</p>
  
  <blockquote>
    <p>Remark: This code is working with .cer extensions (DER &amp; Base 64).</p>
  </blockquote>
  
  <p>Anyone please help to identify the possible root clause?</p>
  
  <p>Thanks.</p>
  
  <p>PS. VS2010, Windows Server 2008 R2</p>
  
  <p>Edit1: test_public_cert.p7b was exported from public key on another server via mmc console.</p>