Folders and calendar does not synchronize

[edgar3]

Hello everyone, I communicate with you because I have a big problem.
I need to synchronize some folders in an email account.
If I give "Viewer" permissions (you can only see), it does not synchronize.
However, if I give it permissions (role) of "Controller" or "administration", it does synchronize.

In the past, when I gave him the role of "viewer" it worked perfectly (he synchronized the folders and the calendar in reading mode, he could share them). Now, it only works by assigning a "controller" or "administration" role.
Is there any way to synchronize in "viewer" mode? (synchronization with persmison only of reading).
Thanks for everything.
I'm waiting.
Excellent afternoon!
Greetings.

[edgar3]

For example:

When the role is "espectador" (viewer):


This is message error:


But the role is "controlador" (controller) its works


Any ideas???

We need works when the role is viewer.

Thansk in advance!