You didn't say how far (days past ovulation, if you know it, or cycle day) you are. Are you sure you're not further along than you think you are? When hcg gets to a certain level sometimes pregnancy tests don't work correctly and the lines will start getting lighter instead of darker. If you think this is a possibility, dilute your urine with water - say 50% urine to 50% water - and see if the lines become darker. If you still don't see a line or if you don't think you're that far along, as the above poster said it is probably because your urine was diluted from drinking throughout the day.