Hi there, we have checked your account and it's ok. Have you successfully set the tag for tasks? Click the upper right of "..." select “Tag Filter" from the drop-down menu, then select tags in the tag list to filter the task of the current box. Click the link below to learn more: http://faq.doit.im/android_4.html#59

If you still can not search the tasks by the tag, please log out and re-login to check.