Cannot access the custom view in lookup field

Hi All,

I am trying to implement custom view in lookup field. On a form I am trying to show the products of a particular type. Code :

var onLoad = function (executionContext) {
        Xrm.Page.getControl("x_stdcontract").addPreSearch(function () {
            addLookupFilter();
        });
}
function addLookupFilter() {
        var viewId = "{33143774-772F-E511-941A-0050568236F9}";
        var viewDisplayName = "PSC";

        fetchXml = "<fetch version='1.0' output-format='xml-platform' mapping='logical' distinct='false'>"
                        + "<entity name='product'>"
                            + "<attribute name='name' />"
                            + "<attribute name='productnumber' />"
                            + "<attribute name='productid' />"
                            + "<attribute name='externalid' />"
                            + "<order attribute='productnumber' descending='false' />"
                            + "<filter type='and'>"
                                + "<condition attribute='category' value='66' operator='eq'/>"
                                + "<condition attribute='type' value='980930000' operator='eq'/>"
                            + "</filter>"
                        + "</entity>"
                    + "</fetch>";
        var layoutXml = "<grid name='resultset' object='1' jump='productid' select='1' icon='1' preview='1'>"
                                      + "<row name='result' id='productid'>"
                                          + "<cell name='name' width='300' />"
                                          + "<cell name='externalid' width='150' />"
                                      + "</row>"
                        + "</grid>";

        Xrm.Page.getControl("x_stdcontract").addCustomView(viewId, "product", viewDisplayName, fetchXml, layoutXml, false);
    }
but still I am not getting the desired result. I am getting those values that were set on that field with a particular system view. But I want to override that system view and have the custom view attached to it.
Please let me know where I am missing it. I think I am too close of solving it.

Thank you.