title: ACR 122u NFC reader doesn't connect via USB: return error
body: <p>Im developing a NFC reading system with C#, according to given sample codes with SDK I cannot connect the device with the application. Sometimes it return unknown error code <strong>(-2146434967)</strong> which is not handled in the sample application codes.
  <img src="https://i.stack.imgur.com/of4OL.png" alt="enter image description here"></p>
  
  <p>But sometimes it return error code <strong>6</strong>, which is a constant <code>public const int SCARD_SPECIFIC = 6;</code> and describe as </p>
  
  <pre><code>/*===============================================================
      ' This value implies the card has been reset and specific 
      ' communication protocols have been established.
   '===============================================================*/
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/K1MC8.png" alt="enter image description here"></p>
  
  <p>I don't know how to proceed, does somebody have any idea?</p>
  
  <p>Thanks</p>