HSA max contribution is $0?

I'm a single person, and switched jobs this year. My new job has a HDHP and I contributed $1400 over 4 months. I selected "Self Only" coverage for the 4 months, and "None" for the other months, since I had a non-HDHP at the previous job. Turbotax is telling me my max HSA contribution is $0. Any idea why??