problem with session variables

Hello,

I am having a problem I think with session variables. On a page I have 4 buttons a user can click from and each of those buttons has a random number associated with it. When the timer reaches zero, one of the buttons is able to be clicked on and a user earns a credit. It works most of the time, However some times it does not store the correct random number for the button. Here is some of the code:

This picks which button will be allowed to click on:

Randomize Timer 'Randomize Function
rndNumber = Int((RND * 4)+1)

If rndNumber = 1 then
Session("KeyCheck") = rndKey1
End If

If rndNumber = 2 then
Session("KeyCheck") = rndKey2
End If

If rndNumber = 3 then
Session("KeyCheck") = rndKey3
End If

If rndNumber = 4 then
Session("KeyCheck") = rndKey4
End If

This next part then takes the random number associated with the button the user clicks and compares it to button that was chosen:

If Request("Encrypt") <> Session("KeyCheck") Then

If it does not match the user is taken back to the logon screen. I cannot figure out why it works most of the time and then there are a few times where the user gets redirected back to the login page even though they clicked on the correct button.

Any help would be appreciated,

Jeff Harnisch