Unable to call Web API controller method with ajax in Asp .Net

Unable to call Web API controller method using ajax jquery in Asp.Net.

$(document).ready(function () {
    $.ajax({
        url: '/UnitsAPI/GetZones',
        method: 'GET',
        dataType: 'json',
        contentType: 'application/json; charset=utf-8',
        data: { "knownCategoryValues": 1, "category": Zone },
        success: function (response) {
            // $('#lblData').html(JSON.stringify(response));
        },
        error: function (error) {
            console.log(error);
        }
    });
});

Web API controller method,

[HttpGet] public IHttpActionResult GetZones(string knownCategoryValues, string category) { SqlConnection sqlConn = new SqlConnection(); DataSet ds = new DataSet();

        string strConn = GetConnectionInfo();
        sqlConn = new SqlConnection(strConn);

        sqlConn.Open();
        int stateID = 1;
        NonCellUnit unit = new NonCellUnit();
        List<Unit> unitList = new List<Unit>();
        unitList = unit.GetChildUnits(stateID, true);

        return Ok(unitList);
    }