Wrong date

Hello,
your tool is very clever it test even if you use the right day of the week.
But there is a little problem. This check is done with the wrong calender. Where can I change the calender in your tool ?

My exemple:
I typed “monday 28th july 2014”
The message says “the 28th july is a Saturday and not a Monday”
But I am right, the 28th is realy a monday.

Where did you try this, at languagetool.org, or in the stand-alone application, …? I cannot reproduce the problem, for “Monday, 28 July 2014” I don’t get an error message.