Error when selecting Date Range for Dynamic Charts

Hi,

I recently created a dashboard which includes various dynamic charts for different columns of data in a separate tab.

When I created it in July I added a Start and End date option for which you can put the dates in that you want to be plotted on the charts. To begin with this worked perfectly and the charts were plotting data dynamically for the date range chosen.

Since the month of July ended I have not been able to get it do the the same, and when I put it different dates I get an error saying 'Date Must be in Correct Range', 'Please Re-enter date'.

The most confusing thing is that when I click cancel on the error box that pops up, the charts plot the new date range I have put in for a split second, and then quickly return to the state they were previously.

Has anyone come across this problem before?

Any help is much appreciated!

Thanks!

Any workbook or code to look at?