To clarify about testing to soon is that there is a list of about 40 different body conditions that could attribute to this including natually occuring antibodies.
Hi, testing to early is a common cause as well as the below:
Laboratory equipment (eg. pipettes, microtiter trays, incubators, washers, and ELISA readers) must be available
· Constant supply of electricity, and regular maintenance of equipment
· Skilled technicians
· Accurate storage and testing temperatures