Hi Johan,
Include and Hide are quite different settings.
If a field is not included, it is not there. It cannot be hidden, or unhidden later. So use this setting when you're deciding what fields to include, or exclude from the form.
The Hide setting is dynamic - the fields are there, just not visible. They can be toggled on and off during the life of the form.
So for a field which is only visible when taskType is 'Registration' or 'RequestForStaff, the HIDE condition would be;
(p_web.GetSessionValue('LOG:TaskType')<>'RequestForStaff' AND p_web.GetSessionValue('LOG:TaskType')<>'Registration')
Note that this is a case-sensitive comparison, so be careful with the possible values of TaskType.
On the TaskType field, Client-Side tab, in the reset list, add this dependent field to the list.
cheers
Bruce