code behind the event_click is not carried out

Hi,
I have a LinkButton_event problem.
I have 2 page's (aspx) the Default page and the Category page thy both use  the same MasterPage.
On the MasterPage i have set 3 LinkButtons and set the LinkUrl  to the Category Page.

When i'm on my Category page, and i'm debugging this page,(run it) and i click the LinkButton, the code behind the LinkButton_click_event is execute and set an session variable.

But when i'm on my Default page, and i'm debugging this page, and i click the LinkButton, the code behind the LinkButton_click_event is not be execute, it only goes to the Category page and not set my session variable.

what is going wrong??????? and how can i resolve this problem of my.

thanks