Issue with JSDO count method

Hi there, I am trying to get Telerik JSDO DataSource to work.

I am following all the examples and guides and it works until I want to implement serverSide paging.

Then I need to implement count method ... I am happily doing that with the following annotations and signature:

@openapi.openedge.export(type="REST", useReturnValue="false", writeDataSetBeforeImage="false").
@progress.service.resourceMapping(type="REST", operation="invoke", URI="/count?filter=~{filter~}", alias="", mediaType="application/json").
METHOD PUBLIC VOID count( INPUT filter AS CHARACTER, OUTPUT numRecs AS INTEGER):

But as soon as I am trying to use it:

dataSource: {
serverPaging: true,
serverFiltering: true,
serverSorting: true,
// batch: true,
filter: { field: "product_category", operator: "eq", value: "SVC" },
type: "jsdo",
transport: {
jsdo: "dsProduct",
countFnName: "count"

I am getting the following error: Could not locate method ''count'' with matching signature in class

The OE is 11.6.1 PAS, Telerik 2016.1.412.

I was trying to look for the countFnName documentation to get some more info about the requirements for the count method, but so far no luck.

Any idea? Thanks!

tom.+