Soo confused !! 🤷‍♀️

So ive taken quiet a few tests , all cheapy ones and then this morning with fmu i took a cheapy one and a fr but i can see a line on the cheepy one but not on the first response one ?? Am i right in thinking a lines a line if ive seen a vvvvvvvvvvvf line on most of the cheap ones ive done or because the fr said no then it deffo a no ?? HELP ??