Visited slides being re-counted in SL3

Hello,

I have a progress bar on my master slide with a radio button to count visited slides. For most slides, the progress bar works fine; once a slide has been visited, it won't be counted again if the user goes back. However, there are several slides in the project that are counted every time the user visits the slide. 

Does anyone know why these slides are being re-counted? Please let me know!

Thank you,

 

 

Sean