getting access token with OAuth
===

I am trying to get around this OAuth issue of getting an access token from Instapaper, it says in their site that they don't **there is no request-token/authorize workflow** and they said this is pretty similar to what twitter does, so here's what I did:

    - (void)getXAuthAccessToken
    {
    	OAConsumer *consumer = [[[OAConsumer alloc] initWithKey:CONSUMER_KEY secret:CONSUMER_SECRET] autorelease];
    	
    	OAMutableURLRequest *request = [[OAMutableURLRequest alloc] initWithURL:[NSURL URLWithString:INSTAPAPER_CLIENT_OAUTH_URL]
    																   consumer:consumer
    																	  token:nil // xAuth needs no request token?
    																	  realm:nil   // our service provider doesn't specify a realm
    														  signatureProvider:nil]; // use the default method, HMAC-SHA1
    	
    	[request setHTTPMethod:@"POST"];
    	
    	[request setParameters:[NSArray arrayWithObjects:
                                [OARequestParameter requestParameterWithName:@"x_auth_mode" value:@"client_auth"],
                                [OARequestParameter requestParameterWithName:@"x_auth_username" value:self.username],
                                [OARequestParameter requestParameterWithName:@"x_auth_password" value:self.password],
                                nil]];		
    	
        
        
        AFHTTPRequestOperation *requestOAuth = [[AFHTTPRequestOperation alloc] initWithRequest:request];
        [requestOAuth setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject){
            NSLog(@"RESPONSE OBJECT IS %@", responseObject);
        }failure:^(AFHTTPRequestOperation *operation, NSError *error){
            NSLog(@"ERROR IS %@", error);
        }];
        
        [requestOAuth start];
        
    }

Any idea why this is constantly giving me a 401?