Hi Hanna
Ive just started using these this month and got a smilie yesterday.
I used them last month and didnt manage to get a smilie, but I think this was down to timing being off.
Are you doing it properly? As the first time I used them I peed on the stick then inserted into the holder and kept getting an error message.

I then read the destructions and figured I had to insert stick into holder before peeing on it!
Im very impatient, I never read the destructions.....far too little time!!!
If your doing it correctly I would take it back and get another quick sharpish!