Redirect to dashboard instead of redirect to add form
Drp, Welcome to stackexchange!

I guess userdata link is the one you have created through extension/plugin and is also registered using xml and have menu rebuild. When menu link is not registered in CiviCRM it will default redirect to CiviCRM dashboard page. 

If you haven't registered than


Register menu link using hook_civicrm_xmlMenu.
Rebuild menu by running /civicrm/menu/rebuild?reset=1 or Navigate to CiviCRM >> Administer >> System Settings >> Cleanup Caches and Update Paths >> Cleanup Caches.


HTH

Pradeep