CRM 2011 - Custom column required is bypassed in outlook

I have custom column (Date) in a Appoitment form which is made required based on another option column (If column InfoFlag is set to 'yes' then make the Date column required). It works fine when the Appointment form is opened in CRM web (http://crm), but for some reason when the Appointment form is opened in Outlook the required column is bypassed. It shows a red asterisk beside the Date column that it's required field, but allows the user to save the form even if the Date is not entered. Any Idea what could be done?

Thanks !