Can pregnancy tests be wrong?

I missed my period 16 days ago so I was really worried and took a pregnancy test at se supposed 5 weeks (last week) that i am supposed to be pregnant if I am.

The was really sensitive 25mlu test turned out negative but I did it at night and maybe my urine mas diluted?

So I did another one yesterday even more sensitive of 10mlu at 6pm I saw my urine and it wasn’t that clear so the test turn out negative again.

I don’t know if pregnancy test can give you false negative results? If I am 5-6 weeks the hcg levels should be high right? Yo detect that? Even more if is a sensitive test.