Tracking Ovulation

So I started tracking my ovulation this month...I’ve been using the First response digital which it only calls for 1 test in the morning and have not had an LH surge with it (currently on day 17) However yesterday I picked up a cheap brand and took a test later that night and it said I was ovulating. Does this make sense? I tested yesterday around 5:30am with the first response (no LH surge), tested at 8:00pm with a cheapie (LH surge) and then tested again this morning around 5:30am with the first response and again no LH surge. HELP!!