Cannot edit row when the primary key is a string contains space

Hi,
I have a table that contains 2 columns:

+-------------+-----------+
| category    |  level   |
+-------------+-----------+
| Cat         |     1     |
| Cat A       |     2     |
| Cat B       |     1     |
| ....        | ...       |
+-------------+-----------+

on Client Side I create a simple editor:

editor = new $.fn.dataTable.Editor({
        ajax: url + "json",
        table: "#detail",
        fields: [
            {
                label: "Category",
                name: "category",
                type: "display"
            },
            {
                label: "level",
                name: "level"
            },
        ]
    });

on Server Side (PHP):

$DB  = $this->editorlib->getDatabase();
$ed = new Editor($DB, "category_table","category");
$ed->debug(true);
$ed->fields(
    Field::inst('category')->set(false),
    Field::inst('level')
);
$ed->process($_POST);
$ed->json();

When I tried to update Cat A level value to another value (3), the row is not updated but a new row with category value '0', and level value 3 inserted instead.

+-------------+-----------+
| category    |  level    |
+-------------+-----------+
| Cat         |     1     |
| Cat A       |     2     |
| Cat B       |     1     |
| 0           |     3     |
+-------------+-----------+

Debug log:

{
   "data":[
      {
         "DT_RowId":"row_0",
         "category":"0",
         "level":3
      }
   ],
   "debug":[
      {
         "query":"SELECT  category as \"category\" FROM  category_table WHERE category = :where_0 ",
         "bindings":[
            {
               "name":":where_0",
               "value":"0",
               "type":null
            }
         ]
      },
      {
         "query":"UPDATE  category_table SET  level = :level WHERE category = :where_0 ",
         "bindings":[
            {
               "name":":level",
               "value":"3",
               "type":null
            },
            {
               "name":":where_0",
               "value":"0",
               "type":null
            }
         ]
      },
      {
         "query":"SELECT  category as \"category\", level as \"level\" FROM  category_table WHERE category = :where_0 ",
         "bindings":[
            {
               "name":":where_0",
               "value":"0",
               "type":null
            }
         ]
      }
   ]
}

From the log above we can see that the binding for ':where_0' is incorrect. It should be "Cat A".

However if I edit the 'Cat' Category, it works fine.

If it's possible, I would like to avoid changing the database structure and add a new primary key.

Thank you.
Danny.