I have multiselect dropdown sending parameters to a controller to have the results returned to the view and bound by a isGrid .  I can send 15 multiselect items with no issue, but if I send more than 15, I get the following error in my console. I wrote a simple .ajax call to do the same thing and I'm able to pass all the parameters and receive the results with no problem. 

infragistics.ui.grid.framework.js:30 Uncaught Error: The remote request to fetch data has failed: ( 404 Not Found )
at $.<computed>.<computed>._renderData (infragistics.ui.grid.framework.js:30)
at $.<computed>.<computed>._renderData (VM769 jquery-ui-1.10.4.js:401)
at proxy (jquery-2.1.1.js:513)
at Class._errorCallback (infragistics.datasource.js:36)
at fire (jquery-2.1.1.js:3073)
at Object.fireWith [as rejectWith] (jquery-2.1.1.js:3185)
at done (jquery-2.1.1.js:8253)
at XMLHttpRequest.<anonymous> (jquery-2.1.1.js:8598)

Here's my table tag

 <table id="SitesGrid"></table>

And the javascript that processes the submit. 

$("#ModifiedCriteriaDialogSubmitButton").on('click', function (evt) {
evt.preventDefault();
popCountySelects();
refreshSitesGrid();
});

function popCountySelects() {
var selCounty = $('#CountyLookups').val();
if (jQuery.isArray(selCounty)) {
$('#hdnCounty').val(selCounty.join(','))
}
else {
$('#hdnCounty').val(selCounty)
}

}

function navigateToSite(siteId) {
window.location = '/Checkpoint/Site/DisplaySite?cpsiteid=' + siteId;
}

function navigateToCreateSite() {
window.location = '/Checkpoint/Site/CreateSite';
}

function search() {
common.displayLoadingDialog();
common.toggleWidget('SearchCriteriaWidget');
var parameters = $('#SiteSearchForm').serialize();
var url = searchURL + '/?ticks=' + new Date() + "&" + parameters;
$('#SitesGrid').igGrid('option', 'dataSource', url);
common.hideLoadingDialog();
}

function bindSitesGrid() {
$("#SitesGrid").igGrid({
responseDataKey: 'Records',
width: "100%",
height: "400",
autoGenerateColumns: false,
primaryKey: "CpSiteId",
fixedHeaders: true,
columns: [
{ key: "CpSiteId", headerText: "", hidden: true },
{
key: "MasterRecordNumber",
headerText: "MRN",
dataType: "string",
width: "10%",
template: "<div class='text-left'><a style='cursor:pointer;' onclick='sitesView.navigateToSite(\"${CpSiteId}\");'>${MasterRecordNumber}</a><\div>"
},
{
key: "County",
headerText: "County",
dataType: "string",
width:"10%"
},
{
key: "Roadway",
headerText: "Roadway",
dataType: "string",
width: "10%"
},
{
key: "IntersectingRoadway",
headerText: "Intersecting Roadway",
dataType: "string",
width: "15s%"
},
{
key: "Location",
headerText: "Location",
dataType: "string",
width: "15%"
},
{
key: "Status",
headerText: "Status",
dataType: "string",
width: "10%"
},
{
key: "SubmitDate",
headerText: "Submit Date",
dataType: "date",
width: "10%"
},
{
key: "ApproveDate",
headerText: "Approve Date",
dataType: "date",
width: "10%"
},
{
key: "FileNetDocumentId",
headerText: "",
formatter: formatViewSiteDocumentButton,
width: "10%"
}
],
autoGenerateLayouts: false,
features: [
{
name: 'Sorting',
type: 'remote',
sortUrlKey: 'sort',
sortUrlKeyAscValue: 'asc',
sortUrlKeyDescValue: 'desc',
columnSettings: [
{ columnKey: 'FileNetDocumentId', allowSorting: false }
]
},
{ name: 'MultiColumnHeaders' },
{
recordCountKey: 'TotalRecordsCount',
pageIndexUrlKey: 'page',
pageSizeUrlKey: 'pageSize',
name: 'Paging',
type: 'remote',
pageSize: portalUI.pageSize(),
pageSizeDropDownLocation: 'inpager'
}
]
});

var parameters = $('#SitesModifiedCriteriaForm').serialize();
var url = '/Checkpoint/Sites/Search/?ticks=' + new Date() + "&" + parameters;

$('#SitesGrid').igGrid('option', 'dataSource', url);
}

function refreshSitesGrid() {
common.displayLoadingDialog();
$("#SitesGrid").igGrid("destroy");
bindSitesGrid();
common.hideLoadingDialog();
}