Edit an appointment from my smartphone

Hello and sorry for my bad English,

I recently started using Zextras Suite, and I have a question about ZxMobile.
I use version 1.6.2 of Zextras Suite and Zimbra OSE version 7.2.1 on Ubuntu 10.04 LTS 64bits.

When I create an appointment in my calendar from webmail, I don't have the option to edit it from my phone, I'm read only (iPhone5-iOS 6.0.1).
However, if I create the appointment from my iPhone, I can edit it from the webmail and from the smartphone.
Is this normal?

thank you