Silva Code Description box results in error

I've tried this on three zope instances where I create a 'Silva Source Code' and once I click add and edit it brings me to a screen asking for Title, Script ID, Data Encoding and Description. When ever I edit a Description it results in an error
Error Value: 'zope.i18nmessageid.message.Message' object has no attribute 'set_mapping'
I'm wondering if this is happening for other people too? It seems that if I edit the description of any other thing (such as encapsulate image or multitoc) it works just fine.