Ive taken a clear blue and it has come up negative when i have been pregnant, it was just taken too early...You havent said when you think you may have concieved or if your period is late?
If your period is late and you have taken a test a would take that as a negative.
If your period is not due yet or the day you think you may have concieved was only 1 week or so ago then i would definatly test again on a few days time or when your period is due just to be certain.