JQuery :: Autocomplete Call WCF Service Method

I am trying to use the below code to call a wcf service method for Autocomplete functionality in a TextBox. I have written the following query:

$(document).ready(function () {
$("#<%= txtCompany.ClientID %>").autocomplete [URL], {
dataType: 'json',
parse: function (data) {
var items = data.d;
var parsed = [];
for (var i = 0; i < items.length; i++)
parsed[i] = {
data: [items[i]],
value: items[i],
result: [items[i]]
};
return parsed;
}
});
});

The same query works if I pass a Java Script array variable instead of the wcf service method. The wcf service method contract is:

[OperationContract]
[WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.WrappedRequest, ResponseFormat = WebMessageFormat.Json)]
string[] GetTestCompanyList(string prefixText, int count);