OPK question

Clearblue advances digital has a solid smiley face yesterday at 11 am. My pregmate strips were pretty close to being positive but weren’t quiet there. Tonight I started cramping so I know I ovulated. I took a pregmate strip 2 hours ago before the cramping still negative. Took one just now and it’s finally positive. I thought so highly of pregmate until now. It’s all I’ve used the last 10 months. Now I’m wondering if they’ve been wrong all of this time or the clearblue was wrong.