Undefined error querying a sharepoint list

Question

I have two lists CharitySlots and CharityBooking.CharityBooking has a lookup field into CharitySlots. CharitySlots has a Lookup (calculated field) to count the number of slots taken. I run an event when a slot is selected (dropdown) and would want to query CharitySlots where the field equals the selected dropwon value and pop up a message with the field value.

here is the code that is giving me problems:

function DisplayMessage()
{
          var clientContext = SP.ClientContext.get_current(); 
          var oList = clientContext.get_web().get_lists().getByTitle('CharityDaySlots');
          var camlQuery = new SP.CamlQuery();
          camlQuery.set_viewXml('<Where><Eq><FieldRef Name=\'SlotsOriginal\'/><Value Text=\'Text\'>10 July 2017 08:00</Value></Eq></Where>');

          var collListItem = oList.getItems(camlQuery);
          this.collListItem = oList.getItems(camlQuery);

          clientContext.load(collListItem);

          clientContext.executeQueryAsync(onSucceededCallback, onFailedCallback);


       function onSucceededCallback() {

             var markup = 'Items in the CharityDaySlots list slots 10 July 2017 08:00': <br><br>';  
               //pop up message witht the item in SlotsOriginal field     
             alert(collListItem.get_item('SlotsOriginal'));

       }
       function onFailedCallback(sender, args) {
             alert('Request failed. ' + args.get_message() + '\n' + args.get_stackTrace());

       }

}