Kendo UI > Update Grid > Internal Server Error Generated - php

Question

I've been beating my head against my desk for a few days now… time I asked for help.
I'm trying to update a value within Kendo UI's grid. The grid displays correctly, as does the popup editor. That's where the good times end. Here's the situation:
Click 'Edit' > Popup Opens > Click 'Update' (no change made) > Popup closes. Result = As expected.
Click 'Edit' > Popup Opens > Click 'Cancel' > Popup closes. Result = As expected.
Click 'Edit' > Popup Opens > Update the 'clientName' field > Click 'Update'. Result = Value in the row changes (in the background), popup stays open and a alert is displayed stating 'undefined'. If I then close the popup the change is lost. As part of this process a 500 internal server error is also generated.
Here's my Kendo code:
$(document).ready(function () {
var crudServiceBaseUrl = "assets/data/",
dataSource = new kendo.data.DataSource({
transport: {
read: {
url: crudServiceBaseUrl + "data.clients.php",
},
update: {
url: crudServiceBaseUrl + "data.clients.update.php",
},
create: {
url: crudServiceBaseUrl + "data.clients.create.php",
},
parameterMap: function(options, operation) {
if (operation !== "read" && options.models) {
return {models: kendo.stringify(options.models)};
}
}
},
batch: true,
pageSize: 10,
error: function(e) {
alert(e.responseText);
},
schema: {
data: function(result) {
return result.data || result;
},
total: function(result) {
var data = this.data(result);
return data ? data.length : 0;
},
model: {
id: "clientID",
fields: {
clientID: { editable: false, nullable: true },
clientName: { validation: { required: true } },
}
}
}
});
$("#grid").kendoGrid({
dataSource: dataSource,
pageable: true,
toolbar: ["create"],
columns: [
{ field: "clientID", title: "Client ID" },
{ field: "clientName", title: "Client Name"},
{ command: "edit", title: " ", width: 110 }],
editable: "popup"
});
});
Here's my PHP:
include '../includes/connect.php';
$clientName = mysql_real_escape_string($_POST["clientName"]);
$clientID = mysql_real_escape_string($_POST["clientID"]);
$rs = mysql_query("UPDATE cms_clients SET clientName = '" .$clientName ."' WHERE clientID = " .$clientID);
if ($rs) {
echo json_encode($rs);
}
else {
header("HTTP/1.1 500 Internal Server Error");
echo "Update failed for EmployeeID: " .$clientID;
}
Oh, and I know this code has issues with potential injection. That's step 2.
Any help would be appreciated.
Thanks,
#rrfive