Something isn't configured right. It should remove the tab entirely and not just the tab contents. You're not hiding the tab then, but are hiding all the fields in it. Please provide the conditional configuration of the field causing problems.

Was not speaking about the tab that was supposed to be hidden, but about the 1st tab containing the field whose value has to hide the 2nd tab.

Implicated elements of the configuration:

Tab-1 (Contact Info)
Field-1 Gender (DD 1 select - Male/Female) - Required - Has no conditions

Tab-2 (Info perso) - Condition: Hidden if Field-1 = Female (Reg./Edit/View enabled as two-way)
Field-2 Birthdate (date) - Required - Has no conditions
Field-3 Reg.type (dd 1 select - Private/Company) - Required - Has Conditions when his value = Private to Shown + Required Field-4
Field-4 Job (dd 1 select - Trainer/No trainer)

Case 1:
Field-1 = Female > Tab-2 well hidden, but with Field-2 (still empty) => 'on save' tab-1 show just title (as if we were showing a mistery Tab-2) - see tab-1_closed.png
Can see it again clicking on the tab title but save button is desactivated - see tab-1_open.png





Case 2:
Field-1 = Female > Tab-2 well hidden with Field-2 (not empty), Field-3 selected on Private (=> shows + required Field-4) but Field-4 (nothing selected) => 'on save', requires Field-4 - see job_in Hidden Tab.png




Provisional solution:
Condition in field-1, when his value = Female, to set Non-required all the required fields of Tab-2

Did you tried it?

Now have also noticed that in registration step by step, the supposed to be hidden tab is not hidden but is only hiding his fields.

Show/Hide of tabs seams to be working fine. You've conflicting conditions. You're telling a tab to hide and thus hide all the fields and set all fields as non-required, but you've a field telling another field on that tab that it needs to show and be required.

I understand that it would be a conflict but only if that field is selected to the value telling the other field on that tab to be shown and 'required' (which was not the case in my test and in that case there are no conflicts)

As I don't know where the real problem is coming from, I have taken the time to quickly make a test,setting up another web based on a fresh installation of Joomla 2.5.6 (without any other extensions) + CB Quickstart PRO 1.0.3 package + CBconditional 1.8.8.
- have set joomla to Atomic - Default template
- have added a 'Gender' field (select) in the 'Contact Info' tab
- have created a 'Personal Info' tab with a single required text field: 'Job'
- have put a condition (only condition of the whole CB, so no conflict) in the 'Personal Info' tab to be hidden if 'Gender' = Female

But, when saving (in Edit profile mode or Registration mode), with 'Gender' = Female, the system is still giving me an error message (see screenshot)



Now, to be fair, this 'Required' flag problem is not that important to me, as for reset purpose (caring for clean DB), I will still have to work on field conditions