[Zope] cannot modify security for a file object

[sathya]

I get the following error when trying to modify security for a file objest. Any
ideas why ?. I am using 2.1.4 and the file is a pdf doc

Thanks
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Zope Error

        Zope has encountered an error while publishing this resource. 

        Error Type: AttributeError
        Error Value: tag



        Troubleshooting Suggestions

            The URL may be incorrect. 
            The parameters passed to this resource may be incorrect. 
            A resource that this resource relies on may be encountering an error. 

        For more detailed information about the error, please refer to the HTML source for this
        page. 

        If the error persists please contact the site maintainer. Thank you for your patience. 
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