Post back pages not getting while hit back button in Firefox

please follow the steps that reproduce my problem

Step 1: Go to this URL - http://tender.net.au/OnlineSale.aspx

Step 2: Click on the page number 5 in bottom of the page

Step 3: Click on any one image that goes to item details page

Step 4: Now click on "Browser Back Button" and let me know why it's not going to item listing page

i am using Firefox 3.6.13

please any one let me know wha开发者_运维问答ts the problem :)