Uncaught TypeError while sorting column with type string

Hi, while sorting a column (sType: "string") an TypeError is thrown in line 4038. I created a jsFiddle to show the problem.
http://jsfiddle.net/friek2k/jUEaq/1/ .. Just click a column header to raise the TypeError 'property 'string-a' is not a function'.

Iam using:
jquery 1.9.0
DataTables: 1.9.4
Chrome 24 / Firefox 19

Regards,
Andre