Hi All, How does filter work in Tempo Tasks report? Any examples or tutoria

How does filter work in Tempo Tasks report? Any examples or tutorial will be appreciated. The current filter is not working.
Below is the sample code
=load(
local!pi: a!pagingInfo(startIndex: 1, batchSize: 20),
local!categoryFilter: 1,
with(
local!ds: rule!epGetDataSubset(pagingInfo: local!pi,filters: if(
isnull(local!categoryFilter),
{},
{field:7, operator: "EQUAL", value: local!categoryFilter-1}
)),
a!dashboardLayout(
firstColumnContents: {
a!dropdownFieldByIndex(
label: "Category Filter",
choiceLabels: {"All", "BMW", "Audi", "Merc"},
value: local!categoryFilter,
saveInto: {
local!categoryFilter,
local!pi << rule!updatePagingInfo << rule!returnFirstInput(local!pi, _)
}
),
a!gridField(
label: "My Tasks",
instructions: "A list of all tasks for the current user.",
columns: rule!epActiveTasksReport_Columns(local!ds),
value: local!pi,
saveInto: local!pi,
totalCount: local!ds.totalCount
)})
)
)

You should look at the Query Data Type for an example of where you can implement a queryFilter data type. You need to populate a queryFilter data type to pass in valid query information.
You can find more about queryFilter types at:
forum.appian.com/.../Data_Types

You need to instantiate a queryFilter object and populate it with the valid values within. You are populating a list of values currently for the filter parameter passed into the query rule.

it seems every thing looks fine. this is not working because of incorrect mapping. please check the filed value at before operator.