I have a question about ovulation!

Crystal • Hello my husband and i haveny really been trying to concieve untill here recently but we havent been preventing it! Keep ur fingers crossed! Plz! 😘😂
So last night I took a test..it was positive so me and my husband had sex..I took another test this morning it was negative but took one around 5 pm and it was positive...I'm using clear blue digital..so me and my husband had sex tonight...could the digital tests be wrong? Or could it be negative in the morning and positive at night?