First Response Ovulation

​I just started trying to better track my ovulation with the First Response Ovulation test kit.  Today I took the test and most of the test line is the same darkness as the reference line (probably 3/4 of the line is the same). Does anyone know if it should be the entire line? I have also noticed that each day I take a test, the lines get closer and closer in darkness. According to Glow my most fertile days are the end of this week. Could the test be picking up on a slight surge? Any advice would be appreciated!!