index column

I have include the index column code about this example: https://datatables.net/examples/api/counter_columns.html

If I load the Page the first time, the column index are shown correct. to go to the next page the column index are shown
[object OBJECT]. to go forward or back to the first page the column index did show this object. I have no idea where my problem is. Should I do this on the Server side?

Here the debug Link: debug.datatables.net/iqiriv

Andreas