New Post: UpdateList Items not updating choice column

Background:
I am trying to update a drop down choice field using Update List items. This is a site column used in a custom content type.

Code that I am using is

function UpdateWishList(ListName,varID,PStatus)
{

$().SPServices({
    operation: "UpdateListItems",
    async: false,
    batchCmd: "Update",
    listName: ListName,
    ID: varID,
    valuepairs: [["ParticipantStatus",  "Notification"]],
    completefunc: function(xData, Status) {

    }
});     

}

Options tried:
Instead of passing the variables, hard coded values were passed

I have tried to take the output of xData.responseText, inside completefunc. Execution shows it is success, alert shows the updated data, however, when I check the list, it still has the old value.

I am using SPServices-2013.01.js along with jquery-1.10.2.js

Please help!!!