analytics - Google Tag Manager Data layer events missing data -

we've implemented data layer connection between google tag manager , google analytics. through custom dimension however, see on 3.000 events , 17 records showing data layer's data. how come there's lot of missing data , how retrieve event data?

<script type="text/javascript"> datalayer = []; </script> <!-- google tag manager (...) /-->

if user logs in:

datalayer.push({ 'fb_id': response.id, 'fb_email': response.email, 'fb_name': response.name, 'fb_first_name': response.first_name, 'fb_last_name': response.last_name, 'fb_gender': response.gender, 'fb_link': response.link, 'fb_locale': response.locale, 'fb_timezone': response.timezone, 'event': 'fb_login', });