.net - Guesses Of Session Value Conflicts?

I have a asp.net web form which will submit information to come as emails. Whenever user fill the form and click on submit button,the information user entered will be sent as email.This web form has 4 page. but the web form will not use all 4 page on all requests.

if the user select a particular value in first page, the form will bypass the 3rd page and go the last 4th page(like...page1,2,4). IF it is any other values selected in the first page. form will navigate as page1,2,3,4.

So now my problem is when multiple users access the same website, the value in the first page get combines from different users and the form will act abnormally.Sometime it will bypass sometimes it will not bypass the page3

Show below is the variable decalrations:

Public strRoleType As String = String.Empty
Protected Shared isAreaSelected As Integer = 0
Protected Shared isStoreSelected As Integer = 0
Protected Shared isHeadOfficeSelected As Integer = 0
Protected Shared isRegionSelected As Integer = 0

I guess the problem is with strRoleType variable whether it is getting values from different users.

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