Condition ignored in trigger

Help please:
I'm trying to create a progress bar in my Storyline 360 file and have a variable "ScreensVisitedCount" to measure the number of slides the user has visited. If they go back a slide, I don't want this to count in the tally so I have the following triggers:
Add value 1 to ScreensVisitedCount when the timeline starts on this slide If the state of Test 1 = Normal
Change state of Test 1 to Selected when the timeline reaches time 1s.
Test 1 is a simple shape with the two states normal and selected. 
Despite the state of Test 1 changing to Selected the value of ScreensVisitedCount is still increasing by 1 when the user goes back to a previously visited slide. It seems to totally disregard the condition on the trigger! I have tried setting the slide properties to 'Resume saved state' but it seems to make no difference. Can anyone shed any light on this please?