I tested for 6 days, not line, a lighter line, a little darker for a few days, then no line again. Iam wondering if the tests dye is low or something, ot maybe my LH surge is weak. I did find out form prog levels that I did in fact O, but OPK didnt work out as promised on package. I think Tracey D has said the same thing about OPKs. I would ask RE to run LH tests next time.