In my opinion, you use a really bad approach.
To get there you need
SIMULTANEOUSLY to have true
txtAUserName.Text = ""
txtAUserName.Text = "me555"
txtAPassword.Text = ""
txtAPassword.Text = "9000"
Every time you use
txtXXX.Focus()
program execution go out of your method since it meets "Else".
I think you should use embedded Validation events. Look
here for example.