Table Sort problems sorting Dates and Numbers

Table Sort problems sorting Dates and Numbers

I am using tablesorter.com as my reference for setting up Table Sorting, and while the demo works great within my stuff it does not seem to sort the dates correctly or the numbers, as an example, this is what I get when sorting one colunm? Do I have to define the format of the date? Or when I try and sort numbers.
 
Only Question I have is I am dynamicially creating the Tables in PHP, reading the data from a database or xls file gives the same results.
 
Numbers
9999999
999999
952
900
750
7050
7000
7000
550
550
550
5250
 
expiry_date
31/12/2013
31/12/2012
31/12/2012
31/12/2012
31/12/2012
31/12/2011
31/12/2011
31/08/2012
31/08/2012
31/07/2012