clear blue ovulation test. please help

so I thought this month I would buy an ovulation test kit a clear blue one. well yesterday I finished my af I know you're supposed to start testing a few days after but I thought I'd use one yesterday just see how it works etc. yesterday it showed just a circle. I don't know why but something said to me to check today (day 1 after af) and this picture came up flashing. could this be wrong? it says it's detected hormones leading to ovulation in roughly 3 days? obvosouly I'll test tomorrow but confused could anything interfere with it? not had any medication or anything the only thing I've had was one small bottle of beer last night as I was still on light period so didn't think it would matter. very confused please help