The score is your timer "timw" right?
You add to the timer and right away you set the txt so it shouldn't be any problem with anything interfering with those events as they run one after the other.
Did you make sure that you print the score in the right Txt object?
Also, "Console log" the variable "timw" after you add 1 and press F12 to see if it works
Also, "Console log" the Txt after you set the Txt to the "timw"