Frer question!

Does anyone have trouble with the first response tests ? I know all you guys swear by them, but I swear I keep getting obvious negatives on them but faint positives on the dollar tree tests & also on blue dye. I've had three pregnancies before. 1 completed pregnancy and tested positive with blue dye. 1 miscarriage at 9 weeks positive with blue dye. 1 chemical positive with blue dye . This go around I've gotten faints on blue dye & dollar tree ones. But absolutely nothing on first response. What's the deal ? Lol