Error editing Tax rates with % in title

With Joomla 3.1.1 and Hikashop 2.1.2 Business; When I go to system, taxes, manage rates and I click the Tax namekey:

"VAT 6%", This will result in error:

406 Not Acceptable

An appropriate representation of the requested resource /administrator/index.php could not be found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

If I choose a Tax namekey without % in it, for instance "VAT 0 percent", it will not give the error.

best regards,

Tom

Hi,

Can you please :
1. Tell me if you're using a SEF extension ? if that's the case can you try it without it ?
2. Give me a link to your website for testing purpose ?

Thank you .