Error While porting to D7

Hi,

I have been trying to port the LinkedIn integration module to D7. I have been using the coder module to assist in porting. I have changed the functions to D7 but I keep getting an error

"Notice: Undefined index: linkedin_not_linked in linkedin_auth_form_alter() (line 74 of modules\linkedin\linkedin_auth\linkedin_auth.module)".

This is where the $_SESSION['linkedin_not_linked'] != 1 first appears on the linkedin_auth.module.

It is set in the function below

function linkedin_auth_linkedin_tie_external_login($uid, $token, $secret) {
$_SESSION['linkedin_not_linked'] = 1;
drupal_set_message('No user associated with this LinkedIn account. Please register.');
if (variable_get('linkedin_auth_bypass_register_checks', 1) == 1) {
drupal_goto('linkedin/register/create');
}
drupal_goto('user/register');
}

I think this function is not being called at all. My question is...is this(linkedin_auth_linkedin_tie_external_login) a custom hook or a drupal hook?