Have you followed up with the potential customers you spoke to?
Did they get to see the almost finished product?
It could be dead, or it could be that you're killing it. If you're asking the question, I suggest you may be killing it.
I was in a similar situation in April. I had build a web-app for businesses to schedule their employees. Everybody said it was a great idea, I showed the product around and the businesses said they liked what it did, and asked for a few features to be added.
I ended up getting it into beta testing, and a few more feature requests came in, but the beta testers stopped using it. When I asked them why they weren't using it, I got all sorts of reasons that had nothing to do with the product, more like - this person didn't have access to internet at home (which means that they didn't get the old schedule either), we'll start using it when you have monthly labour cost totals (also something they don't have with excel), etc. etc.
I decided that the product just didn't strike the nerve I was hoping it would.
People can get really excited about an idea and give you a bunch of input and feedback, but you'll know if you've struck a nerve based on usage.