How to apply default instance security when using an entry template with FileNet P8 4.0.

I'm trying to add a document from Workplace by using an entry template. In the entry template creation wizard, I remove all the proposed security and then I get this warning message:

"Removing all explicit permissions from the security list will cause the entry template to use the default class permissions."

That's OK, since I want the created documents to have the default instance security permissions defined for the document class specified for the entry template (in other words, I don't want to use the security provided or defined by the entry template, since I have some custom security defined in the default instance security that I want to be applied to the created instance).

Anyway, when I try to add a document using this entry template with a user with the necessary permissions, I get the following error message:

Error Message:
User does not have permission to finish the operation.

Exception Class:
com.filenet.wcm.toolkit.util.WcmException

Stack Trace:
User does not have permission to finish the operation.

I already confirmed (from FileNet Enterprise Manager) the user is in the groups listed for the "default instance security", I also granted full control to this group but same problem is appearing. Any ideas? I'm omitting or ignoring something?

Thanks in advance.