I'm getting an exception when calling the GetFacetsFor method:

SearchLibrary.GetFacetsFor(Category.FirstOrDefault(c => c.Name == "Bilprodukter"), new List<Facet>());

Stacktrace:

[InvalidOperationException: Could not find facets document: facets/ProductFacets/en]
   Raven.Database.Queries.FacetedQueryRunnerExtensions.ExecuteGetTermsQuery(DocumentDatabase self, String index, IndexQuery query, String facetSetupDoc, Int32 start, Nullable`1 pageSize) +321
   Raven.Client.Linq.RavenQueryInspector`1.GetFacets(String facetSetupDoc, Int32 start, Nullable`1 pageSize) +72
   UCommerce.Search.RavenDB.RavenFacetProvider.GetFacets(IFacetedQueryable`1 facetedQueryable) +533
   UCommerce.Search.SearchLibraryInternal.GetFacetsFor(Category category, IList`1 facets) +728
   Castle.Proxies.Invocations.SearchLibraryInternal_GetFacetsFor.InvokeMethodOnTarget() +128
   Castle.DynamicProxy.AbstractInvocation.Proceed() +116
   UCommerce.Infrastructure.Interceptor.ExceptionLoggingInterceptor.Intercept(IInvocation invocation) +625
   Castle.DynamicProxy.AbstractInvocation.Proceed() +595
   Castle.Proxies.SearchLibraryInternalProxy.GetFacetsFor(Category category, IList`1 facets) +194

Any ideas how to solve this? I'm not having much luck with google.

Should I do anything else than create some facet-fields in my product definitions?