Membership database linking to my application database with Null when accessed UserID

I have two databases - the aspnetdb on the Membership Login side (standard), and my own application database.  Since UserID is primary key in aspnetdb and PersonID is unique in my application, I decided to add one more field - UserID into my PersonID table to link the two databases together. 
To insert UserID created in aspnetdb into my application, I tried to used this code on the raised event of new user created:
 Protected Sub CreateUserWizard1_CreatedUser(ByVal sender As ...