[c#] C#, Looping through dataset and show each record from a dataset column

I believe you intended it more this way:

foreach (DataTable table in ds.Tables)
{
    foreach (DataRow dr in table.Rows)
    {
        DateTime TaskStart = DateTime.Parse(dr["TaskStart"].ToString());
        TaskStart.ToString("dd-MMMM-yyyy");
        rpt.SetParameterValue("TaskStartDate", TaskStart);
    }
}

You always accessed your first row in your dataset.