Word doesn't work in the server side if I am not logged in

When I tried to open a word application on the server by

 Application ap = new Application();

I got this error

Retrieving the COM class factory for component with CLSID {000209FF-0000-0000-C000-000000000046} failed due to the following error: 8000401a The server process could not be started because the configured identity is incorrect. Check the username and password. (Exception from HRESULT: 0x8000401A).

If I logged in a remote connection and tried it will work but when I disconnect it will not.

It think it is a security and permission issue but I don't know where. I am using IIS 8 and windows server 2012.

Don't try to suggest to use OpenXml or say that Microsoft doesn't recommend that, I want to use Microsoft Office 2013.