SmartSearch filter SKUPrice by range

Hi,

In KenticoCMS V7.0 (hotfix 94 applied) ,I have a smart search dialog that let the user to specify price range. when the user clicks on search , i create a query like this :

skuprice:[(double)0.0 TO (double)300000.0] or skuprice:[0 TO 300000] or +skuprice:[0 TO 300000]

**this is my search snippet inside the results webpart:**
SearchParameters parameters = new SearchParameters()
            {
                SearchFor = "skuprice:[(double)0.0 TO (double)300000.0]"/*searchText*/,
                SearchSort = SearchHelper.GetSort(srt),
                Path = path,
                ClassNames = DocumentTypes,
                CurrentCulture = culture,
                DefaultCulture = defaultCulture,
                CombineWithDefaultCulture = CombineWithDefaultCulture,
                CheckPermissions = CheckPermissions,
                SearchInAttachments = SearchInAttachments,
                User = (UserInfo)CMSContext.CurrentUser,
                SearchIndexes = Indexes,
                StartingPosition = startPosition,
                DisplayResults = displayResults,
                NumberOfProcessedResults = numberOfProceeded,
                NumberOfResults = 0,
                AttachmentWhere = AttachmentsWhere,
                AttachmentOrderBy = AttachmentsOrderBy,
                BlockFieldOnlySearch = BlockFieldOnlySearch,
            };

            // Search
            DataSet results = SearchHelper.Search(parameters);

but results dataset always null. what is going wrong here and how i can make this work properly?

Analizer Type : Standard

SKUPrice has been set to searchable

Thank you