Property not found in the template, which have suitable atribute

[Lewoniewski]

Hello!

Wikipedia template http://en.wikipedia.org/wiki/Template:Infobox_officeholder have atribute "term_start" and is used in plenty of Wiki-articles.

But in DBpedia mapping statistics http://mappings.dbpedia.org/server/templatestatistics/en/?template=Infobox_officeholder the property "term_start" doesn't have instances ("property is mapped but not found in the template definition").

Why?