Version 0.5 seems to break parts of the graph output for Semantic Result Formats (or vice versa). It will not show the labels, colors or legend. I was able to fix this by downgrading to version 0.4.14. --Dgennaro 17:19, 18 October 2012 (UTC)
Topic on Extension talk:Validator
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Thanks for notifying me - the problem is in SRF, and I will get to it soonish so it's not in the 1.8 rel :)
This should be fixed on master now.