Clearblue digital opk

Ok question... I started using the Clearblue digital opk’s not the advanced ones just the regular digital ones and this app says I should ovulate tomorrow but when I’ve been testing the last couple days the test line is super faint when I eject the stick and I know you’re not supposed to look at the lines with the digital tests but I was still wondering should it be getting darker leading up to ovulation or can it go from faint when I have the empty circle to dark when I have the smiley face