Earlier I used a FRER test using urine that had been kept in a cup from this morning and it came up negative. I've just done another internet cheapie and can see a very faint line again, still not a strong line but slightly darker than yesterday. I would have expected a FRER to be more sensitive than the cheap one so is it like that it's negative or could the fact that I used urine that had been stored for about 4 hours affect it?