DllNotFoundException when web application p/invokes a win32 DLL

问题

I get this error when my web application p/invokes a win32 dll (Player.dll)

System.DllNotFoundException: Unable to load DLL 'Player.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

at Player.PlayerProxy.Initialize()
atRunaware.WpfBrowserApp.Player.Page1.PlayFile(Object sender, RoutedEventArgs e)

The application is written in WPF (XBAP).

I've the following info in the .manifest file. Although all .Net DLLs are mentioned in <dependency> tags, the win32 dll is mentioned in tag. Why this difference?

 <file name="Win32DLL\Player.dll" size="620544">
    <hash>
      <dsig:Transforms>
        <dsig:Transform Algorithm="urn:schemas-microsoft-com:HashTransforms.Identity" />
      </dsig:Transforms>
      <dsig:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
      <dsig:DigestValue>EwahNz1qPEyGmnCXusKji4ZTA78=</dsig:DigestValue>
    </hash>
  </file>

来源：https://stackoverflow.com/questions/4790823/dllnotfoundexception-when-web-application-p-invokes-a-win32-dll