The facets doesn't display.

I have a year field in my content. The field value can go from 2000 to 2012, and it is numeric field. I tried to implement this as a slider, but when I do it, all the facets vanish and when I look at the Solr Server log, it gives the error : SolrException : Stats cab only facet on single-valued fields, not : is_field_year

Any help would be very helpful.

keto