Call to undefined function: drupal_system_listing() error when trying to run manually first time

Hi, I receive the following error when trying to run the updates for first time. I use poormanscron not real cron. could it be due to this or a bug?

it sounds like a very useful module so I'd really like to get it working!
thanks for your help
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Available updates
Last checked: Never Check manually
No update data is available. To fetch data, you may need to run cron.

http://-mysiteurl-/admin/logs/updates/force-check:

Fatal error: Call to undefined function: drupal_system_listing() in /home/aliak/public_html/modules/update_status/update_status.module on line 122