I never really found clearblue to be that reliable, especially in the early stages. Like I stated in wobbles thread, I didnt start using CB until atleast 6 weeks along and not once did I use a CB digital, for some reason I didnt really trust them.
I did have a thin line once, but that turned out to be a weird evap line and I have never really trusted that brand since that day because we basically had a false positive as far as I was concerned. This evap line occured within minutes which is why I thought I was pregnant.