tryin for a baby

hiya...i took a test 2 days ago i still have it n says neg now i done 1 yesterday n woke up n its got a vvv faint line.....so i have both test but the 1 off 2days ago is neg n 1 off yesterday shows a vvv faint line....what could it be cause surely the 1 off 2days ago sould hav a faint line too but hasnt helpppp