targets as a string not working?

jmarcv

http://apptest.sellersourcebook.com/members/wsb/dt1.html
TH elements assigned a class, targets refers to the class.
pretty sure this is basically right out of the docs.
What am I doing wrong?

FireBug:
TypeError: col is undefined
if ( col.mData === i ) {
jquery....bles.js (line 6429)

<table id=example>
<tr>
<TH class='c1'>1 ---</TH>
<TH class='c2'>2 ---</TH>
<TH class='c3'>3 ---</TH>
<TH class='c4'>4 ---</TH>
</tr>
</table> <hr>


<script>
data=[
    {
        "name":       "Tiger Nixon",
        "position":   "System Architect",
        "salary":     "3120",
        "start_date": "2011/04/25",
        "office":     "Edinburgh",
        "extn":       "5421"
    },
    {
        "name":       "Garrett Winters",
        "position":   "Director",
        "salary":     "5300",
        "start_date": "2011/07/25",
        "office":     "Edinburgh",
        "extn":       "8422"
    }
]

$("#example").DataTable( {
    data: data,
    columnDefs: [
        { "data": "name",targets": "c1" },
        { "data": "position" ,targets": "c4"},
        { "data": "salary" ,"targets": "c2"},
        { "data": "office" ,"targets": "c3"}
    ]
} );