Maintaining the same controller

[eluser]ReSTe[/eluser]
Hi guys,

i've a little problem. In the index function of my controller i show the view page that permits to do the login. After the login the parameters are passed to a controller function that saves the user in a session etc.etc. The problem is when i call others function of the controller it seems that codeigniter will create another istance of the controller and all the previous declared data (objects and session variables) are lost. why?

for example in a simply login form, the action of the form is verificalogin/

verificalogin is a function of my controller...

where i'm wrong?

thanks a lot, and forgive my poor english