Could Neutral Results For THC Test Be Due To Detoxification Of Body?

I took a test and it came back with nothing for thc wasnt positive or negative being sent to lab I drank 20oz bottle of water before test then almost peed on myself and they wouldn't let me use the bathrokm because they said I wouldn't be able to pee for a while and I said oh well not going to use the bathroom on my self then I went to the restroom and after drank another 20oz bottole of water and cams back as not line at all so sent to lab for further testing???? Did also take a detox ? Help