How to call Facebook auth.getSession (REST API) method using OAuth token?

Issue is about interactions between Facebook REST and Graph API .

I'm building a Facebook application. Once I have a valid OAuth access token I try to incloke auth.getSession method by accessing the URL

http://api.facebook.com/method/auth.getSession?access_token=...

and I get back errors like this

<error_response xsi:schemaLocation="http://api.facebook.com/1.0/ http://api.facebook.com/1.0/facebook.xsd">
  <error_code>100</error_code>
  <error_m开发者_运维技巧sg>The parameter auth_token is required</error_msg>
  <request_args list="true">...</request_args>
</error_response>

So I called auth.createToken method immediately after that , and token was returned ok . Then I try to call auth.getSession once again by accessing this URL:

http://api.facebook.com/method/auth.getSession?auth_token=...

I just get a different error like the one shown below

<error_response xsi:schemaLocation="http://api.facebook.com/1.0/ http://api.facebook.com/1.0/facebook.xsd">
  <error_code>101</error_code>
  <error_msg>Invalid API key</error_msg>
  <request_args list="true">...</request_args>
</error_response>

So how could I invoke auth.getSession method if I only have a valid OAuth token ?