title: Vtiger: I can't add a To Do event
body: <p>If I got to calendar, click on To Do, then try to add an event, the form pops up, I fill it out, press save, but no Event gets added. 
  In the SQL error log's I see an error like this:</p>
  
  <pre><code>2011-09-29 14:57:07 EDT ERROR:  null value in column "visibility" violates not-null constraint
  2011-09-29 14:57:07 EDT STATEMENT:  insert into
  vtiger_activity(activityid,subject,date_start,time_start,time_end,due_date,status,eventstatus,priority,sendnotification,activitytype,visibility,duration_hours,duration_minutes,location,recurringtype,notime) 
  values('235','Testing','2011-09-29','19:50',NULL,'2011-09-29','Not Started',NULL,'High','0','Task',NULL,NULL,NULL,NULL,NULL,'0')
  </code></pre>
  
  <p>So, for some reason, it is trying to add a To-Do while inserting null values. My biggest problem is that I cannot locate the origin of the query. So, basically, the most important thing I am asking is what file takes the data that was input into the todosave form and turns it into a query.</p>
  
  <p>I don't know if many people on here use Vtiger, but I couldn't figure this out so I went ahead and posted anyway. The official documentation is not very helpful in my opinion.</p>
  
  <p>Thanks for everything, have a good day.</p>