Ladies, help!!

Okay ladies so I've been testing with clearblue digital & the past 3 days I've gotten high fertility (flashing smiley) but  I had to buy a new box since I ran out & this morning I used the new monitor thing & got a complete negative so I was so confused I used another strip on my old monitor and got the flashing smiley again. Anybody have problems like his with these?  Thanks so much ❤️