Creating acquirable metadata item

Hello together

Trying to add a new metadata item to the Silva Extra metadata set (a 
StringField) I wanted to make the metadata item acquirable. After 
selecting 'Yes' for 'Enable Acquisition' and pressing 'edit metadata 
element' the following error is displayed:

Error Type: ConfigurationError
Error Value: Required Values may not be Acquired

Any suggestions what is happening?

Regards
Sam

P.S. Silva 1.3-all, Zope 2.7.7-final, Python 2.3.5, win32 xp. Here the 
full traceback:


Time      2005/09/27 12:33:19.932 GMT+2
User Name (User Id)     admin (admin)
Request URL     
http://localhost:8080/silva/service_metadata/collection/silva-extra/test1/editElementPolicy
Exception Type     ConfigurationError
Exception Value     Required Values may not be Acquired

Traceback (innermost last):

    * Module ZPublisher.Publish, line 101, in publish
    * Module ZPublisher.mapply, line 88, in mapply
    * Module ZPublisher.Publish, line 39, in call_object
    * Module Products.SilvaMetadata.Element, line 113, in editElementPolicy

ConfigurationError: Required Values may not be Acquired

-- 
Samuel Schluep | ETH Zürich
Center for Organizational and Occupational Sciences (ZOA)
Unit Man-Machine Interaction
+41 1 632 74 24 | [email protected] | http://www.zoa.ethz.ch