Sandra, i totally agree with Heather. It may be not him. May be something unidentified. And sperm test at lab is easy and also results will be accurate.
I would strongly suggest that your partner gets tested at the lab at your doctor's/RE's office, instead of relying on an at-home test. Much more reliable. As for the reason, it could be him, or it could just be in the "unexplained" category (which many of the couples on here are struggling with), but either way, it would be good to rule out any problems with the sperm count/quality first. Best of luck with everything!