Dynamic Data source error in PowerBI Service

Hello pawankarki23 - I was able to get this to work by using a dataflow Gen2 and making a few modifications to the code.  I also changed the date parameter to a data offset in number of days and provided some additional examples of how you can further parmeterize this, should you wish to do so.

let
    // Define Parameters (these should be defined in Power BI as query parameters)
    _Org = orgName,
    _Project = projectName,
    _TeamName = teamName,
    _ProjectType = projectType,
    _DateOffset = startDateOffsetInDays,

    // Calculate the start date in DateTimeZone format.
    _StartDate = DateTimeZone.ToText(Date.AddDays(DateTimeZone.FixedUtcNow(), _DateOffset), "yyyy-MM-ddTHH:mm:ssZ"),

    // Determine the appropriate board name based on project template
    //BoardName = if _ProjectType = "Scrum" then "Backlog items" else "Stories",
    _BoardName = if _ProjectType = "Scrum" then "Stories" else "Backlog Items",  // I had to use this one to get results for my project

    // Encode URL parts
    _EncodedProject = Uri.EscapeDataString(_Project),
    _EncodedTeamName = Uri.EscapeDataString(_TeamName),
    _EncodedBoardName = Uri.EscapeDataString(_BoardName),

    // Build OData URL
    Url = "https://analytics.dev.azure.com/" & _Org & "/" & _EncodedProject & "/_odata/v4.0-preview/WorkItemBoardSnapshot?"
        &"$apply=filter( "
            &"Team/TeamName eq '" & _TeamName & "' "
            &"and StartDate lt now() "
            & "and BoardName eq '" & _BoardName & "' "
            &"and DateValue gt " & _StartDate & " "
// Additional examples that could be included
//            &"and IsCurrent eq true "
//            &"and startswith(Area/AreaPath,'" & varAreaPathPrefix & "') "
//            &"and StateCategory ne '" & varStateCategory_Excl & "' "
//            &"and DateValue le now()  "
//            &"and DateValue ge Iteration/StartDate "
//            &"and DateValue le Iteration/EndDate "
//            &"and Iteration/StartDate le now()  "
//            &"and Iteration/EndDate ge now() "
//            &"and WorkItemType eq 'Task' "
        &") "
            &"/groupby( "
            &"(Team/TeamName,Area/AreaPath,DateValue,ColumnName,LaneName,State,AssignedTo/UserName,WorkItemType),  "
            &"aggregate($count as Count) "
        &") &$orderby=DateValue,State", // additional example
//        &"&$top=100 ", // additional example

    // Result
    data = OData.Feed(Url, null, [Implementation = "2.0", OmitValues = ODataOmitValues.Nulls, ODataVersion = 4]),
    RemoveComplexColumns = Table.RemoveColumns(data, Table.ColumnsOfType(data, {type table, type record, type list, type nullable binary, type binary, type function}))
in 
    RemoveComplexColumns

You can also trigger this to run using a data pipeline and let the pipeline hold your list of teams/parameter values and the dataflow can interate through those.  Please let me know if you'd like me to help with that.