Basic Doubt in Suite CRM

Hi all,
Now,We are using suite crm for our marketing organization.We create task for everyone in suite crm but actual problem is sometimes they related person field is empty.what is the problem acquire the filed is empty ?.
I here attached the screen shot of that page with marked with red circle.anyone can help this problem\

Clearly the task isn’t being related to a user record, how are you creating the tasks? via workflow?